View source for Key to the Moss Genera of North America North of Mexico

{{Treatment/ID
|accepted_name=Key to the Moss Genera of North America North of Mexico
|accepted_authority={{Treatment/AuthorLink|Dale H. Vitt}}{{Treatment/AuthorLink|William R. Buck}}
|publications=
|basionyms=
|synonyms=
|volume=Volume 28
|mention_page=
|treatment_page=
}}<!--

--><p>This key to the genera of North American mosses is intended to complement not replace the keys to genera included with each family treatment in the Flora. It is a somewhat modified version of a key written earlier (D. H. Vitt and W. R. Buck 1992) to honor Howard A. Crum on his retirement from the University of Michigan.</p><!--

--><div class="treatment-key">
==Keys==
<div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-0">Primary Key</h3>
{| class="wikitable fna-keytable"
|- id="key-0-1"
|1
|Gametophytes seemingly absent (consisting only of protonemata); capsules asymmetric; setae papillose.
|[[Buxbaumia|Buxbaumia]]
|- id="key-0-1"
|1
|Gametophytes present (with obvious leaves); capsules and setae various.
|[[#key-0-2| > 2]]
|- id="key-0-2"
|2
|Laminal cells arranged in a network of narrow, green cells alternating with large hyaline cells; branches usually in clusters.
|[[Sphagnum|Sphagnum]]
|- id="key-0-2"
|2
|Laminal cells of one kind (green), or if two kinds, branches never in clusters.
|[[#key-0-3| > 3]]
|- id="key-0-3"
|3
|Leaves attached in 2 rows on opposite sides of stem (distichous).
|[[#key-0-4| > 4]]
|- id="key-0-4"
|4
|Leaves appearing split at base, consisting of 2 vaginant laminae clasping stem and base of leaf above (equitant).
|[[Fissidens|Fissidens]]
|- id="key-0-4"
|4
|Leaves with expanded bases, not clasping leaf above.
|[[#key-0-5| > 5]]
|- id="key-0-5"
|5
|Leaves ecostate; protonemata luminous.
|[[Schistostega|Schistostega]]
|- id="key-0-5"
|5
|Leaves with single costa; protonemata not luminous.
|[[#key-0-6| > 6]]
|- id="key-0-6"
|6
|Vegetative leaves with smooth mucro; perichaetial leaves with smooth subula.
|[[Bryoxiphium|Bryoxiphium]]
|- id="key-0-6"
|6
|All leaves with papillose, linear subula.
|[[Distichium|Distichium]]
|- id="key-0-3"
|3
|Leaves attached all around stem (foliate stems sometimes flattened [complanate]).
|[[#key-0-7| > 7]]
|- id="key-0-7"
|7
|Leaves without lamellae or filaments on adaxial costal surface (but propagula sometimes present).
|[[#key-0-8| > 8]]
|- id="key-0-8"
|8
|Leaves deeply lobed, lobes linear-terete.
|[[Takakia|Takakia]]
|- id="key-0-8"
|8
|Leaves never lobed, flattened (sometimes concave with margins inrolled or recurved).
|[[#key-0-9| > 9]]
|- id="key-0-9"
|9
|Leaves ecostate, costa short and double, double or single to 1/3 leaf length, or single with 2 or 3 lateral spurs.
|[[#key-1|Subkey A]]
|- id="key-0-9"
|9
|Leaves with single costa to at least mid leaf.
|[[#key-2|Subkey B]]
|- id="key-0-7"
|7
|Leaves with lamellae or filaments on adaxial costal surface (excluding propagula).
|[[#key-0-10| > 10]]
|- id="key-0-10"
|10
|Leaves with filaments on adaxial costal surface.
|[[#key-0-11| > 11]]
|- id="key-0-11"
|11
|Leaf margins reflexed to revolute.
|[[Crossidium|Crossidium]]
|- id="key-0-11"
|11
|Leaf margins broadly inrolled (mostly obscuring filaments).
|[[Aloina|Aloina]]
|- id="key-0-10"
|10
|Leaves with lamellae on adaxial costal surface.
|[[#key-0-12| > 12]]
|- id="key-0-12"
|12
|Leaves bordered with elongate marginal cells.
|[[Atrichum|Atrichum]]
|- id="key-0-12"
|12
|Leaves without elongate marginal cells.
|[[#key-0-13| > 13]]
|- id="key-0-13"
|13
|Leaves ciliate at distal part of hyaline sheath.
|[[Bartramiopsis|Bartramiopsis]]
|- id="key-0-13"
|13
|Leaves eciliate.
|[[#key-0-14| > 14]]
|- id="key-0-14"
|14
|Distal leaf margins 2-stratose with paired, multicellular teeth; leaf apices with slender, smooth, caducous awns.
|[[Lyellia|Lyellia]]
|- id="key-0-14"
|14
|Distal leaf margins 1-stratose with single teeth or entire; leaf apices muticous or with serrate awns.
|[[#key-0-15| > 15]]
|- id="key-0-15"
|15
|Lamellae 2 – 4; leaves hyaline awned; plants small, less than 5 mm; peristome absent or rudimentary and fragile.
|[[Pterygoneurum|Pterygoneurum]]
|- id="key-0-15"
|15
|Lamellae 4 – 50; leaves mostly not awned; plants mostly larger; peristome of 32 or 64 persistent teeth.
|[[#key-0-16| > 16]]
|- id="key-0-16"
|16
|Lamellae distinctly wavy.
|[[#key-0-17| > 17]]
|- id="key-0-17"
|17
|Distal leaf margins not bordered.
|[[Oligotrichum|Oligotrichum]]
|- id="key-0-17"
|17
|Distal leaf margins with border of hyaline, short-rhombic cells.
|[[Psilopilum|Psilopilum]]
|- id="key-0-16"
|16
|Lamellae straight.
|[[#key-0-18| > 18]]
|- id="key-0-18"
|18
|Calyptrae naked or with few hairs.
|[[#key-0-19| > 19]]
|- id="key-0-19"
|19
|Distal abaxial leaf lamellae and teeth absent.
|[[Meiotrichum|Meiotrichum]]
|- id="key-0-19"
|19
|Distal abaxial leaf lamellae and/or teeth present.
|[[Oligotrichum|Oligotrichum]]
|- id="key-0-18"
|18
|Calyptrae densely hairy.
|[[#key-0-20| > 20]]
|- id="key-0-20"
|20
|Capsules present.
|[[#key-0-21| > 21]]
|- id="key-0-21"
|21
|Capsules sharply 4-angled.
|[[Polytrichum|Polytrichum]]
|- id="key-0-21"
|21
|Capsules cylindric or bluntly 2 – 4-angled.
|[[#key-0-22| > 22]]
|- id="key-0-22"
|22
|Capsules with stomata; lumina of apical cells of lamellae pyriform.
|[[Polytrichastrum|Polytrichastrum]]
|- id="key-0-22"
|22
|Capsules without stomata; lumina of apical cells of lamellae not pyriform.
|[[Pogonatum|Pogonatum]]
|- id="key-0-20"
|20
|Capsules absent.
|[[#key-0-23| > 23]]
|- id="key-0-23"
|23
|Apical cells of lamellae papillose.
|[[#key-0-24| > 24]]
|- id="key-0-24"
|24
|Apical cells elliptic-pyriform.
|[[Polytrichastrum|Polytrichastrum]]
|- id="key-0-24"
|24
|Apical cells rounded, quadrate or oblate.
|[[Pogonatum|Pogonatum]]
|- id="key-0-23"
|23
|Apical cells of lamellae smooth or with faint cuticular ridges.
|[[#key-0-25| > 25]]
|- id="key-0-25"
|25
|Plants larger; leaves with or without awns.
|[[Polytrichum|Polytrichum]]
|- id="key-0-25"
|25
|Plants small, less than 6 mm; leaves never awned.
|[[Pogonatum|Pogonatum]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-1">Subkey A</h3>
{| class="wikitable fna-keytable"
|- id="key-1-1"
|1
|Leaves appearing ecostate, but with costae single and occupying entire leaf area, thus lamina appearing multistratose.
|[[#key-1-2| > 2]]
|- id="key-1-2"
|2
|Leaves lanceolate; green cells 4-sided in transverse section.
|[[Leucobryum|Leucobryum]]
|- id="key-1-2"
|2
|Leaves ligulate; green cells 3-sided in transverse section.
|[[Octoblepharum|Octoblepharum]]
|- id="key-1-1"
|1
|Leaves ecostate, costae very short and single, or double; lamina always 1-stratose.
|[[#key-1-3| > 3]]
|- id="key-1-3"
|3
|Distal laminal cells papillose or prorulose.
|[[#key-1-4| > 4]]
|- id="key-1-4"
|4
|Leaf apices hyaline.
|[[#key-1-5| > 5]]
|- id="key-1-5"
|5
|Laminal cell papillae 1 or 2, forked; capsules immersed, smooth; perichaetial leaf margins ciliate; widespread.
|[[Hedwigia|Hedwigia]]
|- id="key-1-5"
|5
|Laminal cell papillae 1, simple; capsules exserted, ribbed; perichaetial leaf margins entire; restricted to w North America.
|[[Pseudobraunia|Pseudobraunia]]
|- id="key-1-4"
|4
|Leaf apices concolorous.
|[[#key-1-6| > 6]]
|- id="key-1-6"
|6
|Laminal cells multipapillose.
|[[#key-1-7| > 7]]
|- id="key-1-7"
|7
|Papillae arranged in rows over lumina; laminal cells more than 5:1.
|[[Taxithelium|Taxithelium]]
|- id="key-1-7"
|7
|Papillae randomly arranged over lumina; laminal cells less than 4:1.
|[[#key-1-8| > 8]]
|- id="key-1-8"
|8
|Leaf apices obtuse; stems complanate-foliate.
|[[Erpodium|Erpodium]] / [[Solmsiella|Solmsiella]]
|- id="key-1-8"
|8
|Leaf apices short-acuminate; stems symmetrically foliate.
|[[Braunia|Braunia]]
|- id="key-1-6"
|6
|Laminal cells 1-papillose or prorulose.
|[[#key-1-9| > 9]]
|- id="key-1-9"
|9
|Stems 2-or 3-pinnate, forming ascending series of flat, frondose tiers.
|[[Hylocomium|Hylocomium]]
|- id="key-1-9"
|9
|Stems simple or 1-pinnate, not forming ascending series of fronds.
|[[#key-1-10| > 10]]
|- id="key-1-10"
|10
|Leaves plicate.
|[[#key-1-11| > 11]]
|- id="key-1-11"
|11
|Costae extending beyond mid leaf; leaves spreading to squarrose.
|[[Rhytidiadelphus|Rhytidiadelphus]]
|- id="key-1-11"
|11
|Costae short; leaves falcate-secund.
|[[Ctenidium|Ctenidium]]
|- id="key-1-10"
|10
|Leaves not plicate.
|[[#key-1-12| > 12]]
|- id="key-1-12"
|12
|Plants reddish black, tightly attached to rock.
|[[Andreaea|Andreaea]]
|- id="key-1-12"
|12
|Plants green, on various substrates.
|[[#key-1-13| > 13]]
|- id="key-1-13"
|13
|Plants minute, less than 2 mm, acrocarpous.
|[[Ephemerum|Ephemerum]]
|- id="key-1-13"
|13
|Plants large, more than 1 cm, pleurocarpous.
|[[#key-1-14| > 14]]
|- id="key-1-14"
|14
|Costae extending to near leaf apex.
|[[Callicostella|Callicostella]]
|- id="key-1-14"
|14
|Costae ending below mid leaf.
|[[#key-1-15| > 15]]
|- id="key-1-15"
|15
|Alar cells many, oblate to rounded, extending up margins; restricted to Pacific Northwest.
|[[Nogopterium|Nogopterium]]
|- id="key-1-15"
|15
|Alar cells few, mostly quadrate, scarcely extending up margins; widespread.
|[[#key-1-16| > 16]]
|- id="key-1-16"
|16
|Medial laminal cells less than 5:1.
|[[#key-1-17| > 17]]
|- id="key-1-17"
|17
|Stem and branch leaves differentiated.
|[[Heterocladium|Heterocladium]]
|- id="key-1-17"
|17
|Stem and branch leaves similar.
|[[#key-1-18| > 18]]
|- id="key-1-18"
|18
|Leaves broadly ovate, strongly concave; apices obtuse to obtuse-apiculate.
|[[Myurella|Myurella]]
|- id="key-1-18"
|18
|Leaves lanceolate to ovate-lanceolate, weakly concave or flat; apices acute to acuminate.
|[[#key-1-19| > 19]]
|- id="key-1-19"
|19
|Leaf apices acute; margins serrulate only distally; propagula often present in leaf axils; n North America.
|[[Pterigynandrum|Pterigynandrum]]
|- id="key-1-19"
|19
|Leaf apices acuminate; margins serrulate throughout; propagula absent; e United States.
|[[Schwetschkeopsis|Schwetschkeopsis]]
|- id="key-1-16"
|16
|Medial laminal cells more than 5:1.
|[[#key-1-20| > 20]]
|- id="key-1-20"
|20
|Basal row of laminal cells with large prorula at proximal end.
|[[Dacryophyllum|Dacryophyllum]]
|- id="key-1-20"
|20
|Basal row of laminal cells smooth.
|[[#key-1-21| > 21]]
|- id="key-1-21"
|21
|Apical laminal cells much shorter than medial cells.
|[[Taxiphyllum|Taxiphyllum]]
|- id="key-1-21"
|21
|Apical laminal cells scarcely differentiated.
|[[#key-1-22| > 22]]
|- id="key-1-22"
|22
|Leaf apices acute; laminal cells prorulose only at distal ends.
|[[Leptohymenium|Leptohymenium]]
|- id="key-1-22"
|22
|Leaf apices slenderly acuminate; laminal cells prorulose at both ends.
|[[Chryso-hypnum|Chryso-hypnum]]
|- id="key-1-3"
|3
|Distal laminal cells smooth (rarely with minute cuticular roughenings).
|[[#key-1-23| > 23]]
|- id="key-1-23"
|23
|Leaf apices with hyaline awn.
|[[#key-1-24| > 24]]
|- id="key-1-24"
|24
|Laminal cells 2:1 or less, oblate-hexagonal throughout; peristome absent.
|[[Erpodium|Erpodium]]
|- id="key-1-24"
|24
|Laminal cells more than 3:1, basal cells quadrate, distal cells short-rhomboidal; peristome present.
|[[Venturiella|Venturiella]]
|- id="key-1-23"
|23
|Leaf apices concolorous.
|[[#key-1-25| > 25]]
|- id="key-1-25"
|25
|Plants aquatic, submerged at least part of year; leaves keeled or flat.
|[[Fontinalis|Fontinalis]]
|- id="key-1-25"
|25
|Plants sometimes in wet habitats but never submerged; leaves never keeled.
|[[#key-1-26| > 26]]
|- id="key-1-26"
|26
|Plants acrocarpous, usually less than 4 cm.
|[[#key-1-27| > 27]]
|- id="key-1-27"
|27
|Plants on rock.
|[[#key-1-28| > 28]]
|- id="key-1-28"
|28
|Plants reddish black; capsules valvate.
|[[Andreaea|Andreaea]]
|- id="key-1-28"
|28
|Plants greenish brown; capsules with 4 peristome teeth.
|[[Tetrodontium|Tetrodontium]]
|- id="key-1-27"
|27
|Plants on bare soil.
|[[#key-1-29| > 29]]
|- id="key-1-29"
|29
|Protonemata few; capsules globose; calyptrae very small, persistent.
|[[Micromitrium|Micromitrium]]
|- id="key-1-29"
|29
|Protonemata many; capsules ovoid, apiculate; calyptrae campanulate-mitrate, deciduous.
|[[Ephemerum|Ephemerum]]
|- id="key-1-26"
|26
|Plants pleurocarpous, mostly larger.
|[[#key-1-30| > 30]]
|- id="key-1-30"
|30
|Costae single, with 2 or more shorter, supplementary costae at base.
|[[Antitrichia|Antitrichia]]
|- id="key-1-30"
|30
|Costae double, or if single very short and without supplementary costae.
|[[#key-1-31| > 31]]
|- id="key-1-31"
|31
|Costae double, extending to or beyond mid leaf.
|[[#key-1-32| > 32]]
|- id="key-1-32"
|32
|Stem paraphyllia many.
|[[#key-1-33| > 33]]
|- id="key-1-33"
|33
|Stem leaves plicate; bases decurrent.
|[[Hylocomiastrum|Hylocomiastrum]]
|- id="key-1-33"
|33
|Stem leaves not plicate; bases not decurrent.
|[[Loeskeobryum|Loeskeobryum]]
|- id="key-1-32"
|32
|Stem paraphyllia absent.
|[[#key-1-34| > 34]]
|- id="key-1-34"
|34
|Laminal cells thin-walled, lax, abruptly bordered by elongate cells.
|[[Cyclodictyon|Cyclodictyon]]
|- id="key-1-34"
|34
|Laminal cells firm-walled, not or only gradually bordered.
|[[#key-1-35| > 35]]
|- id="key-1-35"
|35
|Plants in mats; leaves falcate-secund at least at branch apices; exostome teeth striate, furrowed.
|[[Trachyxiphium|Trachyxiphium]]
|- id="key-1-35"
|35
|Plants tufted; leaves somewhat contorted when dry but not falcate; exostome teeth papillose, not furrowed[Lepidopilum, see 49. Hookeriaceae, v. 28, p. 248]
|[[#key-1-31| > 31]]
|- id="key-1-31"
|31
|Costae single or double, usually ending just beyond leaf base.
|[[#key-1-36| > 36]]
|- id="key-1-36"
|36
|Leaf apices obtuse; plants small, rare, restricted to mountains of se United States.
|[[#key-1-37| > 37]]
|- id="key-1-37"
|37
|Leaves symmetric, without basal lobe.
|[[Bryocrumia|Bryocrumia]]
|- id="key-1-37"
|37
|Leaves asymmetric, with basal lobe.
|[[Homaliadelphus|Homaliadelphus]]
|- id="key-1-36"
|36
|Leaf apices acute to acuminate, at least apiculate; plants mostly larger, widespread.
|[[#key-1-38| > 38]]
|- id="key-1-38"
|38
|Laminal cells lax, hexagonal.
|[[#key-1-39| > 39]]
|- id="key-1-39"
|39
|Lateral and dorsal leaves with similar areolation; stems irregularly branched.
|[[Hookeria|Hookeria]]
|- id="key-1-39"
|39
|Lateral and dorsal leaves differentiated in areolation; stems pinnate.
|[[Vesicularia|Vesicularia]]
|- id="key-1-38"
|38
|Laminal cells firm-to thick-walled, rounded to linear.
|[[#key-1-40| > 40]]
|- id="key-1-40"
|40
|Leaf bases slenderly long-decurrent.
|[[#key-1-41| > 41]]
|- id="key-1-41"
|41
|Plants small to medium-sized, green; leaves not undulate; laminal cells smooth.
|[[Plagiothecium|Plagiothecium]]
|- id="key-1-41"
|41
|Plants large, whitish; leaves strongly undulate; laminal cells with minute, granular, cuticular papillae.
|[[Buckiella|Buckiella]]
|- id="key-1-40"
|40
|Leaf bases not at all decurrent to broadly auriculate.
|[[#key-1-42| > 42]]
|- id="key-1-42"
|42
|Leaves dimorphic, abaxial ones symmetric, cultriform; with large area of enlarged alar cells on one side of costa.
|[[Pilosium|Pilosium]]
|- id="key-1-42"
|42
|Leaves monomorphic, symmetric; alar cells various.
|[[#key-1-43| > 43]]
|- id="key-1-43"
|43
|Plants slender, threadlike or in thin mats; leaves mostly less than 1 mm.
|[[#key-1-44| > 44]]
|- id="key-1-44"
|44
|Alar cells in 1 basal row, somewhat inflated, rounded.
|[[Hageniella|Hageniella]]
|- id="key-1-44"
|44
|Alar cells few, quadrate.
|[[#key-1-45| > 45]]
|- id="key-1-45"
|45
|Branch leaves more than 0.5 mm.
|[[Homomallium|Homomallium]]
|- id="key-1-45"
|45
|Branch leaves less than 0.5 mm.
|[[#key-1-46| > 46]]
|- id="key-1-46"
|46
|Ecostate or costae very short and double; laminal cells rhombic.
|[[Platydictya|Platydictya]]
|- id="key-1-46"
|46
|Costae short and single; laminal cells rounded-elliptic.
|[[Pseudoleskeella|Pseudoleskeella]]
|- id="key-1-43"
|43
|Plants larger; leaves more than 1 mm.
|[[#key-1-47| > 47]]
|- id="key-1-47"
|47
|Leaves falcate-secund.
|[[#key-1-48| > 48]]
|- id="key-1-48"
|48
|Distal laminal cells oblong-rhombic, ca. 3:1.
|[[#key-1-49| > 49]]
|- id="key-1-49"
|49
|Alar cells few, oblong-quadrate, in 1 or 2 rows along insertion.
|[[Sematophyllum|Sematophyllum]]
|- id="key-1-49"
|49
|Alar cells many, oblate, in many rows extending up margins.
|[[Leucodon|Leucodon]]
|- id="key-1-48"
|48
|Distal laminal cells ± linear, more than 6:1.
|[[#key-1-50| > 50]]
|- id="key-1-50"
|50
|Stems regularly and closely pinnate, featherlike, fronds flat, erect to ascending.
|[[Ptilium|Ptilium]]
|- id="key-1-50"
|50
|Stems irregularly pinnate to unbranched, not featherlike, prostrate to loosely ascending.
|[[#key-1-51| > 51]]
|- id="key-1-51"
|51
|Mature branches erect, producing many conspicuous propagula in distal leaf axils.
|[[Platygyrium|Platygyrium]]
|- id="key-1-51"
|51
|Branches not producing propagula in leaf axils.
|[[#key-1-52| > 52]]
|- id="key-1-52"
|52
|Branches curved-secund when dry, erect when moist; alar cells small, quadrate.
|[[Pylaisia|Pylaisia]]
|- id="key-1-52"
|52
|Branches little altered when dry; alar cells various.
|[[#key-1-53| > 53]]
|- id="key-1-53"
|53
|Alar cells when differentiated quadrate, sometimes enlarged but not inflated.
|[[#key-1-54| > 54]]
|- id="key-1-54"
|54
|Stem paraphyllia present.
|[[Rhytidiopsis|Rhytidiopsis]]
|- id="key-1-54"
|54
|Stem paraphyllia absent.
|[[#key-1-55| > 55]]
|- id="key-1-55"
|55
|Plants very large (stem leaves 3.5 – 5 mm); stems ascending to erect; leaves plicate.
|[[Rhytidiadelphus|Rhytidiadelphus]]
|- id="key-1-55"
|55
|Plants smaller (stem leaves less than 3.5 mm); stems prostrate to ascending; leaf plication various.
|[[#key-1-56| > 56]]
|- id="key-1-56"
|56
|Alar cells absent or very few; pale propagula often clustered in leaf axils.
|[[Isopterygiopsis|Isopterygiopsis]]
|- id="key-1-56"
|56
|Alar cells distinctly differentiated; propagula absent, or if present, not clustered in leaf axils.
|[[#key-1-57| > 57]]
|- id="key-1-57"
|57
|Plants on wet rock in mountain streams.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-1-57"
|57
|Plants in various habitats but not as above.
|[[#key-1-58| > 58]]
|- id="key-1-58"
|58
|Costae to 1/3 leaf length with branches not meeting at base; Alaska, Yukon.
|[[Gollania|Gollania]]
|- id="key-1-58"
|58
|Costae mostly shorter, branches meeting at base; widespread.
|[[Hypnum|Hypnum]]
|- id="key-1-53"
|53
|Alar cells quadrate to oblong, inflated.
|[[#key-1-59| > 59]]
|- id="key-1-59"
|59
|Plants in calcareous fens or marl pools, dark reddish brown; leaf apices obtuse.
|[[Scorpidium|Scorpidium]]
|- id="key-1-59"
|59
|Plants in other habitats, golden to green; leaf apices acute to acuminate.
|[[#key-1-60| > 60]]
|- id="key-1-60"
|60
|Plants on wet rock in mountain streams.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-1-60"
|60
|Plants in various habitats but not as above.
|[[#key-1-61| > 61]]
|- id="key-1-61"
|61
|Alar cells inflated in several rows, walls thick; leaf margins strongly serrate.
|[[Heterophyllium|Heterophyllium]]
|- id="key-1-61"
|61
|Alar cells inflated in 1 (or 2) rows, or if more, walls thin; leaf margins entire to serrulate.
|[[#key-1-62| > 62]]
|- id="key-1-62"
|62
|Stems surrounded by enlarged, thin-walled, hyaline cortical cells (hyalodermis); alar regions large, subdecurrent.
|[[Hypnum|Hypnum]]
|- id="key-1-62"
|62
|Stems surrounded by small, thick-walled, concolorous cells; alar regions in 1 (or 2) rows.
|[[#key-1-63| > 63]]
|- id="key-1-63"
|63
|Plants very shiny; leaves 0.8 – 1.4 mm; distal margins densely serrulate; capsules inclined, asymmetric.
|[[Brotherella|Brotherella]]
|- id="key-1-63"
|63
|Plants slightly shiny; leaves 0.5 – 1.1 mm; distal margins distantly serrulate; capsules erect, symmetric.
|[[Pylaisiadelpha|Pylaisiadelpha]]
|- id="key-1-47"
|47
|Leaves straight.
|[[#key-1-64| > 64]]
|- id="key-1-64"
|64
|Stem leaf apices abruptly contracted to long setaceous point.
|[[#key-1-65| > 65]]
|- id="key-1-65"
|65
|Leaf apices hyaline; alar cells scarcely differentiated.
|[[Iwatsukiella|Iwatsukiella]]
|- id="key-1-65"
|65
|Leaf apices yellow; alar cells inflated, hyaline.
|[[Wijkia|Wijkia]]
|- id="key-1-64"
|64
|Stem leaf apices acute, acuminate or apiculate.
|[[#key-1-66| > 66]]
|- id="key-1-66"
|66
|Leaves squarrose-recurved when dry; apices channeled.
|[[#key-1-67| > 67]]
|- id="key-1-67"
|67
|Stem leaves greater than 2.5 mm; alar cells oblong, somewhat inflated, intramarginal.
|[[Rhytidiadelphus|Rhytidiadelphus]]
|- id="key-1-67"
|67
|Stem leaves less than 2.5 mm; alar cells oblong to subquadrate, inflated or not, marginal.
|[[#key-1-68| > 68]]
|- id="key-1-68"
|68
|Leaves greater than 1.6 mm.
|[[Campylium|Campylium]]
|- id="key-1-68"
|68
|Leaves less than 1.7 mm.
|[[Campylophyllum|Campylophyllum]]
|- id="key-1-66"
|66
|Leaves erect to spreading, or if squarrose only when moist; apices mostly not channeled.
|[[#key-1-69| > 69]]
|- id="key-1-69"
|69
|Plants on wet rock in mountain streams; leaves ovate, concave.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-1-69"
|69
|Plants in various habitats but not as above; leaves various.
|[[#key-1-70| > 70]]
|- id="key-1-70"
|70
|Stems complanate-foliate.
|[[#key-1-71| > 71]]
|- id="key-1-71"
|71
|Alar cells many, quadrate; capsules erect.
|[[Entodon|Entodon]]
|- id="key-1-71"
|71
|Alar cells few, variously shaped; capsules usually inclined.
|[[#key-1-72| > 72]]
|- id="key-1-72"
|72
|Plants on vertical substrates, tree trunks or rock.
|[[Neckera|Neckera]]
|- id="key-1-72"
|72
|Plants on horizontal substrates, rarely on extreme base of trees.
|[[#key-1-73| > 73]]
|- id="key-1-73"
|73
|Leaf margins serrulate throughout.
|[[#key-1-74| > 74]]
|- id="key-1-74"
|74
|Apical laminal cells undifferentiated.
|[[Herzogiella|Herzogiella]]
|- id="key-1-74"
|74
|Apical laminal cells shorter than medial cells.
|[[Taxiphyllum|Taxiphyllum]]
|- id="key-1-73"
|73
|Leaf margins entire or serrulate only distally.
|[[#key-1-75| > 75]]
|- id="key-1-75"
|75
|Rhizoids arising from leaf axils, papillose; leaf margins ± entire.
|[[Isopterygiopsis|Isopterygiopsis]]
|- id="key-1-75"
|75
|Rhizoids arising from below leaf insertion, smooth; leaf margins serrulate distally.
|[[#key-1-76| > 76]]
|- id="key-1-76"
|76
|Pseudoparaphyllia filamentous; annuli not differentiated; sexual condition mostly monoicous.
|[[Isopterygium|Isopterygium]]
|- id="key-1-76"
|76
|Pseudoparaphyllia absent; annuli differentiated; sexual condition mostly dioicous.
|[[Pseudotaxiphyllum|Pseudotaxiphyllum]]
|- id="key-1-70"
|70
|Stems symmetrically foliate.
|[[#key-1-77| > 77]]
|- id="key-1-77"
|77
|Alar cells inflated.
|[[#key-1-78| > 78]]
|- id="key-1-78"
|78
|Stems erect, hyalodermis present; alar cells hyaline, in auricles.
|[[Calliergonella|Calliergonella]]
|- id="key-1-78"
|78
|Stems prostrate, hyalodermis absent; alar cells yellowish, not in auricles.
|[[#key-1-79| > 79]]
|- id="key-1-79"
|79
|Alar cells uniform, without enlarged basal row; stem apices flattened.
|[[Callicladium|Callicladium]]
|- id="key-1-79"
|79
|Alar cells with enlarged basal row; stem apices not flattened.
|[[#key-1-80| > 80]]
|- id="key-1-80"
|80
|Alar regions rounded to insertion; exostome teeth furrowed.
|[[Acroporium|Acroporium]]
|- id="key-1-80"
|80
|Alar regions not rounded to insertion; exostome teeth not furrowed.
|[[#key-1-81| > 81]]
|- id="key-1-81"
|81
|Exostome teeth striate; endostome with evident basal membrane and segments; e North America.
|[[Sematophyllum|Sematophyllum]]
|- id="key-1-81"
|81
|Exostome teeth smooth or faintly papillose; endostome fugacious, appearing absent; restricted to c Florida in oak scrub.
|[[Donnellia|Donnellia]]
|- id="key-1-77"
|77
|Alar cells rectangular to quadrate, not inflated.
|[[#key-1-82| > 82]]
|- id="key-1-82"
|82
|Alar cells many (more than 50), quadrate, regions extending up margins in 12+ rows.
|[[#key-1-83| > 83]]
|- id="key-1-83"
|83
|Stem paraphyllia many.
|[[Alsia|Alsia]]
|- id="key-1-83"
|83
|Stem paraphyllia absent.
|[[#key-1-84| > 84]]
|- id="key-1-84"
|84
|Leaves less than 0.8 mm; laminal cells wit h obscure cuticular roughenings.
|[[Leptopterigynandrum|Leptopterigynandrum]]
|- id="key-1-84"
|84
|Leaves more than 1 mm; laminal cells smooth.
|[[#key-1-85| > 85]]
|- id="key-1-85"
|85
|Alar cells extending up margins more than 1/3 leaf length.
|[[#key-1-86| > 86]]
|- id="key-1-86"
|86
|Secondary stems simple or with few branches.
|[[Leucodon|Leucodon]]
|- id="key-1-86"
|86
|Secondary stems freely subpinnate.
|[[Forsstroemia|Forsstroemia]]
|- id="key-1-85"
|85
|Alar cells extending up margins less than 1/6 leaf length.
|[[#key-1-87| > 87]]
|- id="key-1-87"
|87
|Leaf apices mostly obtuse to acute, rarely acuminate; bases never decurrent; endostome cilia absent; widespread but not in coastal w North America.
|[[Entodon|Entodon]]
|- id="key-1-87"
|87
|Leaf apices acuminate; bases somewhat decurrent; endostome cilia present; restricted to coastal w North America, California to British Columbia.
|[[Tripterocladium|Tripterocladium]]
|- id="key-1-82"
|82
|Alar cells fewer (less than 25), quadrate to rectangular, regions extending up margins in less than 8 rows.
|[[#key-1-88| > 88]]
|- id="key-1-88"
|88
|Plants epiphytic; primary stems creeping, secondary stems erect.
|[[#key-1-89| > 89]]
|- id="key-1-89"
|89
|Secondary stems unbranched; leaves spreading with squarrose apices; propagula common.
|[[Jaegerina|Jaegerina]]
|- id="key-1-89"
|89
|Secondary stems irregularly branched; leaves erect; propagula absent.
|[[Neomacounia|Neomacounia]]
|- id="key-1-88"
|88
|Plants terrestrial or rarely on base of trees; primary and secondary stems not differentiated.
|[[#key-1-90| > 90]]
|- id="key-1-90"
|90
|Stem hyalodermis present; leaf margins serrulate to base.
|[[Herzogiella|Herzogiella]]
|- id="key-1-90"
|90
|Stem hyalodermis absent; leaf margins entire or serrulate distally.
|[[#key-1-91| > 91]]
|- id="key-1-91"
|91
|Leaves plicate.
|[[Orthothecium|Orthothecium]]
|- id="key-1-91"
|91
|Leaves not plicate.
|[[#key-1-92| > 92]]
|- id="key-1-92"
|92
|Leaf apices obtuse-apiculate.
|[[#key-1-93| > 93]]
|- id="key-1-93"
|93
|Plants in fens; stems green, sparsely branched.
|[[Pseudocalliergon|Pseudocalliergon]]
|- id="key-1-93"
|93
|Plants widespread in acidic habitats of boreal forests; stems reddish orange, pinnate.
|[[Pleurozium|Pleurozium]]
|- id="key-1-92"
|92
|Leaf apices acuminate.
|[[#key-1-94| > 94]]
|- id="key-1-94"
|94
|Laminal cells not porose except at insertion; pseudoparaphyllia filamentous; coastal e North America inland to Midwest.
|[[Isopterygium|Isopterygium]]
|- id="key-1-94"
|94
|Laminal cells porose throughout; pseudoparaphyllia absent or foliose; boreal, arctic, and alpine habitats.
|[[Orthothecium|Orthothecium]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-2">Subkey B</h3>
{| class="wikitable fna-keytable"
|- id="key-2-1"
|1
|Stems erect, dendroid or frondose from stipe.
|[[#key-2-2| > 2]]
|- id="key-2-2"
|2
|Leaves bordered by elongate cells.
|[[#key-2-3| > 3]]
|- id="key-2-3"
|3
|Branch leaves dimorphic.
|[[Hypopterygium|Hypopterygium]]
|- id="key-2-3"
|3
|Branch leaves monomorphic.
|[[#key-2-4| > 4]]
|- id="key-2-4"
|4
|Stems ± evenly branched, resembling small palm trees; stem leaves highly modified, triangular, hyaline or with hyaline apices; distal leaves ovate-triangular, flat.
|[[Leucolepis|Leucolepis]]
|- id="key-2-4"
|4
|Stems irregularly branched; proximal stem leaves similar to distal leaves, lingulate, undulate.
|[[Plagiomnium|Plagiomnium]]
|- id="key-2-2"
|2
|Leaves not bordered.
|[[#key-2-5| > 5]]
|- id="key-2-5"
|5
|Stem paraphyllia absent.
|[[#key-2-6| > 6]]
|- id="key-2-6"
|6
|Branch leaf apical laminal cells long-hexagonal; costae slender, tapering toward apex.
|[[Porotrichum|Porotrichum]]
|- id="key-2-6"
|6
|Branch leaf apical laminal cells rhombic; costae s trong, not tapering toward apex.
|[[Thamnobryum|Thamnobryum]]
|- id="key-2-5"
|5
|Stem paraphyllia or filamentous, paraphyllialike structures present.
|[[#key-2-7| > 7]]
|- id="key-2-7"
|7
|Plants epiphytic; stems pinnate, frondose, curled when dry, spreading when moist.
|[[Dendroalsia|Dendroalsia]]
|- id="key-2-7"
|7
|Plants terrestrial (rarely on tree bases); stems dendroid, little altered when dry.
|[[#key-2-8| > 8]]
|- id="key-2-8"
|8
|Branch leaf bases cordate to auriculate, auricles not inflated; stem paraphyllia present; stem leaf margins serrate.
|[[Climacium|Climacium]]
|- id="key-2-8"
|8
|Branch leaf bases long-decurrent, decurrencies of inflated, hyaline cells; stem lamellae present; stem leaf margins entire.
|[[Pleuroziopsis|Pleuroziopsis]]
|- id="key-2-1"
|1
|Stems prostrate to erect, simple to pinnate.
|[[#key-2-9| > 9]]
|- id="key-2-9"
|9
|Plants blackish, tightly attached to rock in arctic and montane areas; capsules valvate.
|[[#key-2-10| > 10]]
|- id="key-2-10"
|10
|Plants on acidic rock; capsules hygroscopic, elliptic when moist, tapering to point.
|[[Andreaea|Andreaea]]
|- id="key-2-10"
|10
|Plants on calcareous rock; capsules not hygroscopic, turbinate, obtuse-conic.
|[[Andreaeobryum|Andreaeobryum]]
|- id="key-2-9"
|9
|Plants greenish to blackish, on various substrates; capsules cleistocarpous or operculate, never valvate.
|[[#key-2-11| > 11]]
|- id="key-2-11"
|11
|Leaves strongly squarrose-recurved; in fens.
|[[Paludella|Paludella]]
|- id="key-2-11"
|11
|Leaves erect to squarrose; in various habitats.
|[[#key-2-12| > 12]]
|- id="key-2-12"
|12
|Stem paraphyllia present.
|[[#key-2-13| > 13]]
|- id="key-2-13"
|13
|Stems complanate-foliate; stem leaves undulate.
|[[Neckera|Neckera]]
|- id="key-2-13"
|13
|Stems symmetrically foliate; stem leaves not undulate.
|[[#key-2-14| > 14]]
|- id="key-2-14"
|14
|Alar regions well differentiated, cells inflated.
|[[#key-2-15| > 15]]
|- id="key-2-15"
|15
|Stem leaves not plicate; paraphyllia foliose, few to many.
|[[Cratoneuron|Cratoneuron]]
|- id="key-2-15"
|15
|Stem leaves deeply plicate; paraphyllia filamentous, many.
|[[Palustriella|Palustriella]]
|- id="key-2-14"
|14
|Alar regions mostly not differentiated, if so, cells not inflated.
|[[#key-2-16| > 16]]
|- id="key-2-16"
|16
|Paraphyllia with cells elongate, more than 5:1, at least at apex.
|[[#key-2-17| > 17]]
|- id="key-2-17"
|17
|Leaf margins entire to serrulate.
|[[Elodium|Elodium]]
|- id="key-2-17"
|17
|Leaf margins strongly serrate distally.
|[[#key-2-18| > 18]]
|- id="key-2-18"
|18
|Medial laminal cells short, oblong to quadrate, with 1 massive central papilla.
|[[Echinophyllum|Echinophyllum]]
|- id="key-2-18"
|18
|Medial laminal cells elongate or shortly oblong, smooth.
|[[#key-2-19| > 19]]
|- id="key-2-19"
|19
|Distal laminal cells linear, more than 8:1; widespread
|[[Hylocomiastrum|Hylocomiastrum]]
|- id="key-2-19"
|19
|Distal laminal cells short, 2 – 5:1; se United States.
|[[Climacium|Climacium]]
|- id="key-2-16"
|16
|Paraphyllia with cells short, 1 – 3:1.
|[[#key-2-20| > 20]]
|- id="key-2-20"
|20
|Paraphyllia with cells papillose.
|[[#key-2-21| > 21]]
|- id="key-2-21"
|21
|Laminal cells 1-papillose.
|[[#key-2-22| > 22]]
|- id="key-2-22"
|22
|Stems 1-pinnate; laminal cells papillose on both surfaces.
|[[Abietinella|Abietinella]]
|- id="key-2-22"
|22
|Stems 2-or 3-pinnate; laminal cells papillose only abaxially.
|[[Thuidium|Thuidium]]
|- id="key-2-21"
|21
|Laminal cells multipapillose.
|[[#key-2-23| > 23]]
|- id="key-2-23"
|23
|Plants large; sexual condition dioicous; laminal cells papillose only abaxially.
|[[Thuidium|Thuidium]]
|- id="key-2-23"
|23
|Plants small; sexual condition autoicous; laminal cells papillose on both surfaces.
|[[#key-2-24| > 24]]
|- id="key-2-24"
|24
|Stems 1-or 2-pinnate; leaves incurved when dry; laminal cells flat; setae smooth or papillose.
|[[Cyrto-hypnum|Cyrto-hypnum]]
|- id="key-2-24"
|24
|Stems 1-pinnate; leaves not incurved when dry; laminal cells strongly bulging; setae smooth.
|[[Rauiella|Rauiella]]
|- id="key-2-20"
|20
|Paraphyllia with cells smooth.
|[[#key-2-25| > 25]]
|- id="key-2-25"
|25
|Laminal cell papillae large, forked or elongate and curved; leaves broadly ovate.
|[[Thelia|Thelia]]
|- id="key-2-25"
|25
|Laminal cell papillae short, simple; leaves lanceolate to ovate-lanceolate.
|[[#key-2-26| > 26]]
|- id="key-2-26"
|26
|Costae pellucid; leaf hair-points usually present.
|[[Claopodium|Claopodium]]
|- id="key-2-26"
|26
|Costae opaque; leaf hair-points absent.
|[[#key-2-27| > 27]]
|- id="key-2-27"
|27
|Stem and branch leaves differentiated.
|[[Haplocladium|Haplocladium]]
|- id="key-2-27"
|27
|Stem and branch leaves similar.
|[[#key-2-28| > 28]]
|- id="key-2-28"
|28
|Laminal cells elongate, oblong-rhombic to oblong-linear.
|[[#key-2-29| > 29]]
|- id="key-2-29"
|29
|Capsules erect, symmetric; endostome segments narrow, not keeled.
|[[Lescuraea|Lescuraea]]
|- id="key-2-29"
|29
|Capsules inclined, asymmetric; endostome segments broader, keeled.
|[[Pseudoleskea|Pseudoleskea]]
|- id="key-2-28"
|28
|Laminal cells isodiametric or nearly so, hexagonal to short-rhombic.
|[[#key-2-30| > 30]]
|- id="key-2-30"
|30
|Capsules erect, symmetric; exostome teeth papillose; mostly e North America.
|[[Leskea|Leskea]]
|- id="key-2-30"
|30
|Capsules inclined, asymmetric; exostome teeth striate; mostly w North America.
|[[Pseudoleskea|Pseudoleskea]]
|- id="key-2-12"
|12
|Stem paraphyllia absent.
|[[#key-2-31| > 31]]
|- id="key-2-31"
|31
|Plants whitish; leaves composed mostly of costa, multistratose, with small green cells enclosed between 2 layers of hyaline cells on both surfaces.
|[[#key-2-32| > 32]]
|- id="key-2-32"
|32
|Green cells in transverse section 4-sided; terrestrial.
|[[Leucobryum|Leucobryum]]
|- id="key-2-32"
|32
|Green cells in transverse section 3-sided; occasionally terrestrial.
|[[Octoblepharum|Octoblepharum]]
|- id="key-2-31"
|31
|Plants greenish to blackish, rarely whitish; leaves usually with conspicuous lamina, if not, green and hyaline cells of ca. equal size, with 1 layer of hyaline cells on either side of green cells.
|[[#key-2-33| > 33]]
|- id="key-2-33"
|33
|Leaf margins strongly incurved to involute, at least when dry.
|[[#key-2-34| > 34]]
|- id="key-2-34"
|34
|Leaf margins incurved when dry or moist.
|[[#key-2-35| > 35]]
|- id="key-2-35"
|35
|Laminal cells smooth; costal stereid band 1.
|[[Indusiella|Indusiella]]
|- id="key-2-35"
|35
|Laminal cells papillose; costal stereid bands 2.
|[[Weissia|Weissia]]
|- id="key-2-34"
|34
|Leaf margins incurved when dry, plane when moist.
|[[#key-2-36| > 36]]
|- id="key-2-36"
|36
|Costal stereid band 1; peristome present.
|[[Plaubelia|Plaubelia]]
|- id="key-2-36"
|36
|Costal stereid bands 2; peristome absent.
|[[Hyophila|Hyophila]]
|- id="key-2-33"
|33
|Leaf margins plane to recurved.
|[[#key-2-37| > 37]]
|- id="key-2-37"
|37
|Plants minute, on soil (or rarely rock), ephemeral, often with persistent protonemata; capsules immersed.
|[[#key-2-38| > 38]]
|- id="key-2-38"
|38
|Capsules operculate.
|[[#key-2-39| > 39]]
|- id="key-2-39"
|39
|Exothecial cells collenchymatous.
|[[Aphanorrhegma|Aphanorrhegma]]
|- id="key-2-39"
|39
|Exothecial cells not collenchymatous.
|[[Physcomitrium|Physcomitrium]]
|- id="key-2-38"
|38
|Capsules cleistocarpous.
|[[#key-2-40| > 40]]
|- id="key-2-40"
|40
|Spores few per capsule, more than 100 µm.
|[[#key-2-41| > 41]]
|- id="key-2-41"
|41
|Leaves broadly ovate or elliptic; apices abruptly narrowed to awn; plants with slender, subterranean rhizomes.
|[[Lorentziella|Lorentziella]]
|- id="key-2-41"
|41
|Leaves oblong to lanceolate; apices acute to subulate; plants not rhizomatous.
|[[Archidium|Archidium]]
|- id="key-2-40"
|40
|Spores many per capsule, less than 60 µm.
|[[#key-2-42| > 42]]
|- id="key-2-42"
|42
|Leaves ovate to broadly ovate; apices abruptly cuspidate to apiculate.
|[[#key-2-43| > 43]]
|- id="key-2-43"
|43
|Distal laminal cells multipapillose.
|[[#key-2-44| > 44]]
|- id="key-2-44"
|44
|Leaf margins plane.
|[[Aschisma|Aschisma]]
|- id="key-2-44"
|44
|Leaf margins revolute.
|[[Tortula|Tortula]]
|- id="key-2-43"
|43
|Distal laminal cells smooth or with 1 conic papilla or bottle-shaped protuberances.
|[[#key-2-45| > 45]]
|- id="key-2-45"
|45
|Distal laminal cells bulging adaxially as bottle-shaped cells.
|[[Microbryum|Microbryum]]
|- id="key-2-45"
|45
|Distal laminal cells smooth or occasionally with conic papillae.
|[[Acaulon|Acaulon]]
|- id="key-2-42"
|42
|Leaves narrowly lanceolate to oblong; costae subpercurrent to subulate.
|[[#key-2-46| > 46]]
|- id="key-2-46"
|46
|Capsules pyriform, neck conspicuous.
|[[Bruchia|Bruchia]]
|- id="key-2-46"
|46
|Capsules globose to broadly elliptic, neck not conspicuously differentiated.
|[[#key-2-47| > 47]]
|- id="key-2-47"
|47
|Costae long-excurrent, at least on perichaetial leaves.
|[[Cleistocarpidium|Cleistocarpidium]] / [[Pleuridium|Pleuridium]]
|- id="key-2-47"
|47
|Costae subpercurrent.
|[[#key-2-48| > 48]]
|- id="key-2-48"
|48
|Leaf margins spinose-serrulate throughout.
|[[Ephemerum|Ephemerum]]
|- id="key-2-48"
|48
|Leaf margins entire or serrulate distally.
|[[#key-2-49| > 49]]
|- id="key-2-49"
|49
|Leaves oblong-lanceolate to obovate.
|[[Physcomitrella|Physcomitrella]]
|- id="key-2-49"
|49
|Leaves lanceolate.
|[[Pseudephemerum|Pseudephemerum]]
|- id="key-2-37"
|37
|Plants mostly larger, on various substrates, mostly not ephemeral, or if so, capsules exserted, protonemata not persistent or not present when mature.
|[[#key-2-50| > 50]]
|- id="key-2-50"
|50
|Capsule neck (hypophyses) as wide or wider than urn; on dung and animal remains.
|[[#key-2-51| > 51]]
|- id="key-2-51"
|51
|Capsules dumbbell shaped when mature; setae hyaline; restricted to the Arctic.
|[[Aplodon|Aplodon]]
|- id="key-2-51"
|51
|Capsules (at least urn) cylindric; setae pigmented; widespread.
|[[#key-2-52| > 52]]
|- id="key-2-52"
|52
|Hypophyses narrowly pyriform, same color or darker than urn; peristome teeth joined in 4's, later in 2's, not chambered.
|[[Tetraplodon|Tetraplodon]]
|- id="key-2-52"
|52
|Hypophyses globose to turbinate, sometimes umbrelliform, color differentiated from urn; peristome teeth sometimes approxima te or fused in pairs, chambered.
|[[Splachnum|Splachnum]]
|- id="key-2-50"
|50
|Capsule neck considerably narrower than urn; on various substrates.
|[[#key-2-53| > 53]]
|- id="key-2-53"
|53
|Leaves dimorphic, lateral ones large, dorsal ones smaller.
|[[#key-2-54| > 54]]
|- id="key-2-54"
|54
|Leaves bordered; stems erect; along Pacific coast.
|[[Epipterygium|Epipterygium]]
|- id="key-2-54"
|54
|Leaves unbordered; stems prostrate; restricted to s Florida.
|[[Racopilum|Racopilum]]
|- id="key-2-53"
|53
|Leaves monomorphic.
|[[#key-2-55| > 55]]
|- id="key-2-55"
|55
|Capsules cleistocarpous; plants rare.
|[[#key-2-56| > 56]]
|- id="key-2-56"
|56
|New Hampshire; on wet soil.
|[[Bruchia|Bruchia]]
|- id="key-2-56"
|56
|Arctic and alpine tundra; on animal-derived substrates.
|[[#key-2-57| > 57]]
|- id="key-2-57"
|57
|Capsules broadest proximally.
|[[Voitia|Voitia]]
|- id="key-2-57"
|57
|Capsules broadest distally.
|[[Tetraplodon|Tetraplodon]]
|- id="key-2-55"
|55
|Capsules operculate; plants rare to common.
|[[#key-2-58| > 58]]
|- id="key-2-58"
|58
|Laminal cell walls nodulose-wavy throughout leaf, sometimes most conspicuous toward leaf base when distal cells short.
|[[#key-2-59| > 59]]
|- id="key-2-59"
|59
|Laminal cells smooth or with raised ridges between lumina (pseudopapillae).
|[[Bucklandiella|Bucklandiella]]
|- id="key-2-59"
|59
|Laminal cells papillose or hyaline leaf awns papillose, papillae over lumina.
|[[#key-2-60| > 60]]
|- id="key-2-60"
|60
|Green laminal cells with tall, conic papillae over lumina.
|[[Niphotrichum|Niphotrichum]]
|- id="key-2-60"
|60
|Green laminal cells with flat papillae over longitudinal walls.
|[[#key-2-61| > 61]]
|- id="key-2-61"
|61
|Hyaline apices present, strongly papillose, decurrent.
|[[Racomitrium|Racomitrium]]
|- id="key-2-61"
|61
|Hyaline apices absent, or if present never papillose or decurrent.
|[[Codriophorus|Codriophorus]]
|- id="key-2-58"
|58
|Laminal cell walls not nodulose-wavy, or only near leaf insertion.
|[[#key-2-62| > 62]]
|- id="key-2-62"
|62
|Leaf hair-points absent, or if present not hyaline.
|[[#key-2-63| > 63]]
|- id="key-2-63"
|63
|Costae narrower, or if broad then ending below leaf apex and not filling it; or if costae broad then plants pleurocarpous.
|[[#key-2-64| > 64]]
|- id="key-2-64"
|64
|Plants pleurocarpous (sporophytes lateral); stems mostly prostrate with lateral branches, often mat-forming, or stems prostrate with erect branches bearing terminal sporophytes (cladocarpous).
|[[#key-3|Subkey C]]
|- id="key-2-64"
|64
|Plants acrocarpous (sporophytes terminal); stems erect, not branched or occasionally branched below inflorescences.
|[[#key-4|Subkey D]]
|- id="key-2-63"
|63
|Costae very broad, occupying 1/3 – 1/2 leaf base and filling subula; plants acrocarpous.
|[[#key-2-65| > 65]]
|- id="key-2-65"
|65
|Alar cells well differentiated.
|[[#key-2-66| > 66]]
|- id="key-2-66"
|66
|Costal guide cells and stereids absent, in transverse section with median layer of green cells enclosed dorsally and ventrally with hyaline cells.
|[[Paraleucobryum|Paraleucobryum]]
|- id="key-2-66"
|66
|Costal guide cells and stereids usually present, without enclosed green cells.
|[[#key-2-67| > 67]]
|- id="key-2-67"
|67
|Inner basal laminal cells not conspicuously differentiated along costa; capsules furrowed; annuli compound; calyptrae usually fringed.
|[[Campylopus|Campylopus]]
|- id="key-2-67"
|67
|Inner basal laminal cells pale, enlarged, broadly rectangular, extending upward along costa; capsules smooth; annuli absent; calyptrae not fringed.
|[[Dicranodontium|Dicranodontium]]
|- id="key-2-65"
|65
|Alar cells poorly differentiated.
|[[#key-2-68| > 68]]
|- id="key-2-68"
|68
|Capsule neck at least as long as urn; costa filling no more tha n 1/3 leaf base.
|[[Trematodon|Trematodon]]
|- id="key-2-68"
|68
|Capsule neck short, inconspicuous; costa filling 1/2 or more of leaf base.
|[[#key-2-69| > 69]]
|- id="key-2-69"
|69
|Leaves 3.5 – 5 mm; distal laminal cells elongate, 75 – 140 µm; brood leaves absent.
|[[Campylopodiella|Campylopodiella]]
|- id="key-2-69"
|69
|Leaves 2 – 3 mm; distal laminal cells rectangular, 25 – 55 µm; brood leaves usually present, often many.
|[[Brothera|Brothera]]
|- id="key-2-62"
|62
|Leaf hair-points present, hyaline.
|[[#key-2-70| > 70]]
|- id="key-2-70"
|70
|Costa broad, filling 1/4 or more of leaf base.
|[[Campylopus|Campylopus]]
|- id="key-2-70"
|70
|Costa narrower than 1/4 leaf base.
|[[#key-2-71| > 71]]
|- id="key-2-71"
|71
|Distal laminal cells densely multipapillose, papillae C -shaped.
|[[#key-2-72| > 72]]
|- id="key-2-72"
|72
|Basal laminal cell end walls thickened; calyptrae large, mitrate.
|[[Encalypta|Encalypta]]
|- id="key-2-72"
|72
|Basal laminal cell end walls not thickened; calyptrae small, cucullate.
|[[#key-2-73| > 73]]
|- id="key-2-73"
|73
|Abaxial costal surface cells thin-walled, differentiated from interior stereids; laminal reaction yellow in 2% KOH.
|[[Tortula|Tortula]]
|- id="key-2-73"
|73
|Abaxial costal surface cells thick-walled, not differentiated from interior stereids; laminal reaction red to orange in 2% KOH.
|[[#key-2-74| > 74]]
|- id="key-2-74"
|74
|Leaf margins plane to revolute; marginal cells similar to laminal cells.
|[[Syntrichia|Syntrichia]]
|- id="key-2-74"
|74
|Leaf margins strongly revolute; marginal cells chlorophyllose, walls thin.
|[[Hilpertia|Hilpertia]]
|- id="key-2-71"
|71
|Distal laminal cells smooth or papillae low, indistinct.
|[[#key-2-75| > 75]]
|- id="key-2-75"
|75
|Laminal cells smooth, lax, hexagonal to rhombic, walls thin.
|[[#key-2-76| > 76]]
|- id="key-2-76"
|76
|Leaves not bordered.
|[[Stegonia|Stegonia]]
|- id="key-2-76"
|76
|Leaves bordered.
|[[#key-2-77| > 77]]
|- id="key-2-77"
|77
|Leaves ovate to broadly lanceolate; distal margins entire to serrulate.
|[[Leptostomopsis|Leptostomopsis]]
|- id="key-2-77"
|77
|Leaves obovate to spathulate; distal margins serrate.
|[[#key-2-78| > 78]]
|- id="key-2-78"
|78
|Distalmost laminal cells quadrate to short-rectangular, 1 – 2:1; capsules erect; peristome reduced.
|[[Brachymenium|Brachymenium]]
|- id="key-2-78"
|78
|Distalmost laminal cells rectangular, 2 – 4:1; capsules inclined to pendent; peristome well developed.
|[[Rosulabryum|Rosulabryum]]
|- id="key-2-75"
|75
|Laminal cells obscurely papillose, rounded to quadrate, walls firm.
|[[#key-2-79| > 79]]
|- id="key-2-79"
|79
|Plants on trees.
|[[Orthotrichum|Orthotrichum]]
|- id="key-2-79"
|79
|Plants on rock and soil.
|[[#key-2-80| > 80]]
|- id="key-2-80"
|80
|Perichaetial leaves differentiated from vegetative leaves in size and shape; capsules immersed.
|[[Schistidium|Schistidium]]
|- id="key-2-80"
|80
|Perichaetial leaves similar to distal vegetative leaves; capsules immersed or exserted.
|[[#key-2-81| > 81]]
|- id="key-2-81"
|81
|Calyptrae scarcely longer than operculum, cucullate or mitrate, smooth.
|[[Grimmia|Grimmia]]
|- id="key-2-81"
|81
|Calyptrae large, covering capsule to middle or below, campanulate-mitrate, striate or plicate.
|[[#key-2-82| > 82]]
|- id="key-2-82"
|82
|Leaves lanceolate; annuli absent; calyptrae plicate.
|[[Coscinodon|Coscinodon]]
|- id="key-2-82"
|82
|Leaves ovate to obovate; annuli well developed; calyptrae striate.
|[[Jaffueliobryum|Jaffueliobryum]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-3">Subkey C</h3>
{| class="wikitable fna-keytable"
|- id="key-3-1"
|1
|Leaves bordered by elongate cells, sharply differentiated from shorter inner cells.
|[[#key-3-2| > 2]]
|- id="key-3-2"
|2
|Plants epiphytic; leaf borders 1-stratose.
|[[Daltonia|Daltonia]]
|- id="key-3-2"
|2
|Plants aquatic; leaf borders 2 – 5-stratose.
|[[#key-3-3| > 3]]
|- id="key-3-3"
|3
|Leaf margins serrate almost to base; leaves ovate-oblong to ovate-lanceolate; apices acuminate; Oregon.
|[[Limbella|Limbella]]
|- id="key-3-3"
|3
|Leaf margins serrulate; leaves ovate, often broadly so; apices bluntly acute; e North America.
|[[Platylomella|Platylomella]]
|- id="key-3-1"
|1
|Leaves not bordered by elongate cells.
|[[#key-3-4| > 4]]
|- id="key-3-4"
|4
|Laminal cells papillose or prorulose.
|[[#key-3-5| > 5]]
|- id="key-3-5"
|5
|Leaves rugose, plicate.
|[[Rhytidium|Rhytidium]]
|- id="key-3-5"
|5
|Leaves not rugose, rarely plicate.
|[[#key-3-6| > 6]]
|- id="key-3-6"
|6
|Laminal cells multipapillose.
|[[#key-3-7| > 7]]
|- id="key-3-7"
|7
|Papillae randomly arranged over cells; laminal cells ± isodiametric.
|[[#key-3-8| > 8]]
|- id="key-3-8"
|8
|Leaves strongly inrolled when dry; marginal basal laminal cells elongate, smooth; sporophytes terminal on branches.
|[[Macromitrium|Macromitrium]]
|- id="key-3-8"
|8
|Leaves loosely erect to contorted when dry; marginal basal laminal cells rounded, papillose; sporophytes lateral.
|[[Anomodon|Anomodon]]
|- id="key-3-7"
|7
|Papillae arranged in 1 row over lumina; laminal cells longer than 3:1.
|[[#key-3-9| > 9]]
|- id="key-3-9"
|9
|Plants stiff, dark green to blackish; leaves ovate, plicate; bases cordate.
|[[Papillaria|Papillaria]]
|- id="key-3-9"
|9
|Plants soft, bright green; leaves lanceolate, not plicate; bases not cordate.
|[[Barbella|Barbella]]
|- id="key-3-6"
|6
|Laminal cells 1-papillose or prorulose.
|[[#key-3-10| > 10]]
|- id="key-3-10"
|10
|Laminal cells 1-papillose over lumina.
|[[#key-3-11| > 11]]
|- id="key-3-11"
|11
|Distal laminal cells linear-flexuose; specialized asexual reproduction by 1-seriate propagula in leaf axils.
|[[Henicodium|Henicodium]]
|- id="key-3-11"
|11
|Distal laminal cells short, 1 – 3:1; specialized asexual reproduction absent or by branchlets.
|[[#key-3-12| > 12]]
|- id="key-3-12"
|12
|Leaves ovate-lanceolate, squarrose when moist; apices narrowed to smooth, pale acumen.
|[[Lindbergia|Lindbergia]]
|- id="key-3-12"
|12
|Leaves oblong-ovate, loosely erect, ± c omplanate; apices bluntly acute.
|[[Stereophyllum|Stereophyllum]]
|- id="key-3-10"
|10
|Laminal cells prorulose.
|[[#key-3-13| > 13]]
|- id="key-3-13"
|13
|Laminal cells 1 – 3:1.
|[[#key-3-14| > 14]]
|- id="key-3-14"
|14
|Leaves little altered when moist; perichaetial leaves scarcely differentiated; capsules exserted.
|[[Lescuraea|Lescuraea]]
|- id="key-3-14"
|14
|Leaves appressed when dry, wide-spreading when moist; perichaetial leaves strongly differentiated; capsules immersed.
|[[#key-3-15| > 15]]
|- id="key-3-15"
|15
|Perichaetia and capsules lateral; peristome double (single in C. ravenelii).
|[[Cryphaea|Cryphaea]]
|- id="key-3-15"
|15
|Perichaetia and capsules terminal; peristome single.
|[[Schoenobryum|Schoenobryum]]
|- id="key-3-13"
|13
|Laminal cells more than 5:1.
|[[#key-3-16| > 16]]
|- id="key-3-16"
|16
|Plants epiphytic; primary stems inconspicuous, creeping, secondary stems erect; costae subpercurrent.
|[[Pireella|Pireella]]
|- id="key-3-16"
|16
|Plants terrestrial and epiphytic; primary and secondary stems not differentiated; costae ending well before apex.
|[[#key-3-17| > 17]]
|- id="key-3-17"
|17
|Leaf bases decurrent; setae rough; capsule s inclined; usually terrestrial.
|[[Bryhnia|Bryhnia]]
|- id="key-3-17"
|17
|Leaf bases not decurrent; setae smooth; capsules erect; epiphytic or saxicolous.
|[[Isothecium|Isothecium]]
|- id="key-3-4"
|4
|Laminal cells smooth.
|[[#key-3-18| > 18]]
|- id="key-3-18"
|18
|Leaf apices rounded-obtuse to truncate, apiculus absent.
|[[#key-3-19| > 19]]
|- id="key-3-19"
|19
|Leaf apices truncate.
|[[Neckeropsis|Neckeropsis]]
|- id="key-3-19"
|19
|Leaf apices rounded-obtuse.
|[[#key-3-20| > 20]]
|- id="key-3-20"
|20
|Distal laminal cells less than 3:1.
|[[#key-3-21| > 21]]
|- id="key-3-21"
|21
|Stems strongly complanate-foliate, little altered when moist; plants shiny.
|[[Homalia|Homalia]]
|- id="key-3-21"
|21
|Stems at best weakly complanate-foliate, strongly incurved when dry, erect when moist; plants dull.
|[[Leptodon|Leptodon]]
|- id="key-3-20"
|20
|Distal laminal cells more than 5:1.
|[[#key-3-22| > 22]]
|- id="key-3-22"
|22
|Alar cells inflated, or well differentiated from basal cells.
|[[#key-3-23| > 23]]
|- id="key-3-23"
|23
|Leaves loosely spreading, slightly concave; in fens.
|[[Calliergon|Calliergon]]
|- id="key-3-23"
|23
|Leaves strongly julaceous, concave; in peatlands or near streams.
|[[#key-3-24| > 24]]
|- id="key-3-24"
|24
|Leaves oblong; apices obtuse; plants yellowish, very shiny, in peatlands.
|[[Straminergon|Straminergon]]
|- id="key-3-24"
|24
|Leaves ovate; apices obtuse to bluntly acute; plants brownish or green, dull or occasionally glossy, along streams and on rock.
|[[Scleropodium|Scleropodium]]
|- id="key-3-22"
|22
|Alar cells not at all inflated, or if different from basal cells then smaller.
|[[#key-3-25| > 25]]
|- id="key-3-25"
|25
|Costal terminal spines present.
|[[Oxyrrhynchium|Oxyrrhynchium]]
|- id="key-3-25"
|25
|Costal terminal spines absent.
|[[#key-3-26| > 26]]
|- id="key-3-26"
|26
|Leaves plane to concave, spreading to loosely imbricate; laminal cells usually more than 7:1; on wet rock; widespread.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-3-26"
|26
|Leaves deeply concave, tightly imbricate; laminal cells mostly less than 7:1; terrestrial; Alaska.
|[[Myuroclada|Myuroclada]]
|- id="key-3-18"
|18
|Leaf apices acuminate to bluntly acute, or apiculus present, minute.
|[[#key-3-27| > 27]]
|- id="key-3-27"
|27
|Distal laminal cells 1 – 2:1.
|[[#key-3-28| > 28]]
|- id="key-3-28"
|28
|Sporophytes terminal on erect branches; distal laminal cells rounded.
|[[#key-3-29| > 29]]
|- id="key-3-29"
|29
|Basal marginal laminal cells short, rounded-quadrate.
|[[#key-3-30| > 30]]
|- id="key-3-30"
|30
|Distal laminal cells not bulging; leaves oblong-lanceolate; calyptrae naked, cucullate.
|[[Drummondia|Drummondia]]
|- id="key-3-30"
|30
|Distal laminal cells strongly bulging; leaves lanceolate; calypt rae hairy, mitrate.
|[[Macrocoma|Macrocoma]]
|- id="key-3-29"
|29
|Basal marginal laminal cells elongate.
|[[#key-3-31| > 31]]
|- id="key-3-31"
|31
|Inner basal laminal cells subquadrate to rounded; calyptrae short, plicate.
|[[Groutiella|Groutiella]]
|- id="key-3-31"
|31
|Inner basal laminal cells linear; calyptrae long, not plicate.
|[[Schlotheimia|Schlotheimia]]
|- id="key-3-28"
|28
|Sporophytes lateral; distal laminal cells rhombic to subquadrate.
|[[#key-3-32| > 32]]
|- id="key-3-32"
|32
|Costae strongly flexuose distally; leaf margins with multicellular teeth.
|[[Herpetineuron|Herpetineuron]]
|- id="key-3-32"
|32
|Costae straight or faintly flexuose; leaf margins entire to serrulate.
|[[#key-3-33| > 33]]
|- id="key-3-33"
|33
|Costae ending in leaf apex.
|[[#key-3-34| > 34]]
|- id="key-3-34"
|34
|Distal laminal cells short-oblong to rhombic, walls firm.
|[[#key-3-35| > 35]]
|- id="key-3-35"
|35
|Costae less than 35 µm wide at base; terrestrial.
|[[Amblystegium|Amblystegium]]
|- id="key-3-35"
|35
|Costae mostly more than 50 µm wide at base; aquatic.
|[[Hygroamblystegium|Hygroamblystegium]]
|- id="key-3-34"
|34
|Distal laminal cells rounded-quadrate to elliptic, walls thick.
|[[#key-3-36| > 36]]
|- id="key-3-36"
|36
|B rood branchlets present, axillary.
|[[Leskeella|Leskeella]]
|- id="key-3-36"
|36
|Brood branchlets absent.
|[[#key-3-37| > 37]]
|- id="key-3-37"
|37
|Alar cells extending to costa; inner basal laminal cells not differentiated; peristome white.
|[[Lindbergia|Lindbergia]]
|- id="key-3-37"
|37
|Alar cells in 5 or 6 rows along margins, not reaching costa; inner basal laminal cells long-rectangular; peristome yellow.
|[[Pseudoleskeella|Pseudoleskeella]]
|- id="key-3-33"
|33
|Costae ending well before leaf apex.
|[[#key-3-38| > 38]]
|- id="key-3-38"
|38
|Secondary stems erect, branched.
|[[#key-3-39| > 39]]
|- id="key-3-39"
|39
|Leaf apices broadly acute; leaves less than 1 mm; w North America.
|[[Bryolawtonia|Bryolawtonia]]
|- id="key-3-39"
|39
|Leaf apices short-acuminate; leaves more than 1 mm; e North America.
|[[Forsstroemia|Forsstroemia]]
|- id="key-3-38"
|38
|Secondary stems not differentiated, prostrate.
|[[#key-3-40| > 40]]
|- id="key-3-40"
|40
|Leaf apices acuminate; leaves often homomallous.
|[[Pseudoleskeella|Pseudoleskeella]]
|- id="key-3-40"
|40
|Leaf apices bluntly acute; leaves erect to spreading.
|[[#key-3-41| > 41]]
|- id="key-3-41"
|41
|Leaves symmetric; exostome teet h rudimentary; se North America.
|[[Clasmatodon|Clasmatodon]]
|- id="key-3-41"
|41
|Leaves obliquely asymmetric at apex; exostome teeth cross striate; boreal and arctic.
|[[Myrinia|Myrinia]]
|- id="key-3-27"
|27
|Distal laminal cells more than 5:1.
|[[#key-3-42| > 42]]
|- id="key-3-42"
|42
|Plants with long, deciduous, flagelliform branches.
|[[Pseudocryphaea|Pseudocryphaea]]
|- id="key-3-42"
|42
|Plants without flagelliform branches.
|[[#key-3-43| > 43]]
|- id="key-3-43"
|43
|Primary stems inconspicuous, creeping, with reduced leaves, secondary stems erect, leafy.
|[[#key-3-44| > 44]]
|- id="key-3-44"
|44
|Secondary stems mostly unbranched.
|[[Jaegerina|Jaegerina]]
|- id="key-3-44"
|44
|Secondary stems irregularly pinnate.
|[[#key-3-45| > 45]]
|- id="key-3-45"
|45
|Secondary stem leaf costae toothed abaxially; branch leaf apices acute.
|[[Bestia|Bestia]]
|- id="key-3-45"
|45
|Costae smooth abaxially; branch leaf apices acuminate.
|[[#key-3-46| > 46]]
|- id="key-3-46"
|46
|Leaf margins revolute nearly throughout, serrate distally, teeth often reflexed; costae often with supplementary costae; w North America (disjunct in Newfoundland).
|[[Antitrichia|Antitrichia]]
|- id="key-3-46"
|46
|Leaf margins reflexed, entire to serrulate; costae without supplementary costae; e North America.
|[[Forsstroemia|Forsstroemia]]
|- id="key-3-43"
|43
|Primary and secondary stems not differentiated.
|[[#key-3-47| > 47]]
|- id="key-3-47"
|47
|Plants aquatic, coarse; costae broad, more than 100 µm wide at base, bluntly excurrent.
|[[#key-3-48| > 48]]
|- id="key-3-48"
|48
|Costae ca. 1/4 width of leaf base; lamina 1-stratose throughout.
|[[Hygroamblystegium|Hygroamblystegium]]
|- id="key-3-48"
|48
|Costae ca. 1/3 width of leaf base; lamina with multistratose streaks.
|[[Donrichardsia|Donrichardsia]]
|- id="key-3-47"
|47
|Plants of various habitats; costae much narrower, ending before apex to excurrent, if excurrent then finely so.
|[[#key-3-49| > 49]]
|- id="key-3-49"
|49
|One side of stems for entire length covered by reddish rhizoidal tomentum; leaves strongly plicate.
|[[Tomentypnum|Tomentypnum]]
|- id="key-3-49"
|49
|Tomentum, if present, restricted to extreme base of stems; leaves plicate or not.
|[[#key-3-50| > 50]]
|- id="key-3-50"
|50
|Leaves falcate-secund.
|[[#key-3-51| > 51]]
|- id="key-3-51"
|51
|Stem hyalodermis present.
|[[#key-3-52| > 52]]
|- id="key-3-52"
|52
|Leaves strongly plicate; margins distinctly denticulate distally.
|[[Sanionia|Sanionia]]
|- id="key-3-52"
|52
|Leaves striolate to plane; margins entire to slightly denticulate.
|[[#key-3-53| > 53]]
|- id="key-3-53"
|53
|Alar cells inflated; in streams.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-3-53"
|53
|Alar cells poorly differentiated; in rich fens.
|[[Scorpidium|Scorpidium]]
|- id="key-3-51"
|51
|Stem hyalodermis absent.
|[[#key-3-54| > 54]]
|- id="key-3-54"
|54
|Plants of upland habitats; le aves plicate.
|[[Brachytheciastrum|Brachytheciastrum]] / [[Brachythecium|Brachythecium]] / [[Sciuro-hypnum]] complex
|- id="key-3-54"
|54
|Plants of wet habitats; leaves not plicate.
|[[#key-3-55| > 55]]
|- id="key-3-55"
|55
|Leaves keeled, distinctly to obscurely 3-ranked; endostome segments connate at apices.
|[[Dichelyma|Dichelyma]]
|- id="key-3-55"
|55
|Leaves not keeled or 3-ranked; endostome segments free.
|[[#key-3-56| > 56]]
|- id="key-3-56"
|56
|Costae excurrent.
|[[#key-3-57| > 57]]
|- id="key-3-57"
|57
|Alar cells poorly differentiated.
|[[Drepanocladus|Drepanocladus]]
|- id="key-3-57"
|57
|Alar cells abruptly inflated.
|[[#key-3-58| > 58]]
|- id="key-3-58"
|58
|Leaf margins entire.
|[[Drepanocladus|Drepanocladus]]
|- id="key-3-58"
|58
|Leaf margins finely denticulate.
|[[Warnstorfia|Warnstorfia]]
|- id="key-3-56"
|56
|Costae subpercurrent.
|[[#key-3-59| > 59]]
|- id="key-3-59"
|59
|Leaf margins finely denticulate at apex.
|[[#key-3-60| > 60]]
|- id="key-3-60"
|60
|Plants greenish; leaf apices acuminate.
|[[Warnstorfia|Warnstorfia]]
|- id="key-3-60"
|60
|Plants reddish; leaf apices acute, acuminate, or rounded-apiculate.
|[[Sarmentypnum|Sarmentypnum]]
|- id="key-3-59"
|59
|Leaf margins entire throughout.
|[[#key-3-61| > 61]]
|- id="key-3-61"
|61
|Plants on rock in mountain streams.
|[[Hygrohypnum|Hygrohypnum]]
|- id="key-3-61"
|61
|Plants in fens and seeps, not on rock.
|[[#key-3-62| > 62]]
|- id="key-3-62"
|62
|Proximal laminal cells porose; Arctic areas.
|[[Pseudocalliergon|Pseudocalliergon]] / [[Loeskypnum|Loeskypnum]]
|- id="key-3-62"
|62
|Laminal cells porose only at extreme insertion; widespread.
|[[#key-3-63| > 63]]
|- id="key-3-63"
|63
|Stems with central strand present.
|[[Drepanocladus|Drepanocladus]]
|- id="key-3-63"
|63
|Stems with central strand absent.
|[[Hamatocaulis|Hamatocaulis]]
|- id="key-3-50"
|50
|Leaves straight or recurved.
|[[#key-3-64| > 64]]
|- id="key-3-64"
|64
|Leaves 3-ranked, conduplicate.
|[[Brachelyma|Brachelyma]]
|- id="key-3-64"
|64
|Leaves not 3-ranked or conduplicate.
|[[#key-3-65| > 65]]
|- id="key-3-65"
|65
|Plants pendulous from branches; stem leaf apices with capillary points; branch leaves strongly recurved; restricted to s Florida.
|[[Zelometeorium|Zelometeorium]]
|- id="key-3-65"
|65
|Plants terrestrial to epiphytic, never pendulous; stem leaf apices with shorter points; branch leaves mostly not strongly recurved; mostly n North America.
|[[#key-3-66| > 66]]
|- id="key-3-66"
|66
|Laminal cells long-hexagonal, less than 8:1.
|[[#key-3-67| > 67]]
|- id="key-3-67"
|67
|Leaves broadly ovate, deeply concave; Alaska.
|[[Myuroclada|Myuroclada]]
|- id="key-3-67"
|67
|Leaves lanceolate to ovate, not or only slightly concave; widespread.
|[[#key-3-68| > 68]]
|- id="key-3-68"
|68
|Plants epiphytic.
|[[#key-3-69| > 69]]
|- id="key-3-69"
|69
|Leaf margins entire; apices gradually acuminate; peristome double, reflexed.
|[[Anacamptodon|Anacamptodon]]
|- id="key-3-69"
|69
|Leaf margins mostly toothed; apices piliferous; peristome single to absent.
|[[Fabronia|Fabronia]]
|- id="key-3-68"
|68
|Plants terrestrial and saxicolous.
|[[#key-3-70| > 70]]
|- id="key-3-70"
|70
|Leaf apices piliferous.
|[[Fabronia|Fabronia]]
|- id="key-3-70"
|70
|Leaf apices acute to acuminate.
|[[#key-3-71| > 71]]
|- id="key-3-71"
|71
|Distal laminal cell walls thick, ends rounded; capsules erect.
|[[Pseudoleskeella|Pseudoleskeella]]
|- id="key-3-71"
|71
|Distal laminal cell walls firm, ends pointed; capsules inclined.
|[[#key-3-72| > 72]]
|- id="key-3-72"
|72
|Plants on soil in dry habitats, especially prairies.
|[[Brachytheciastrum|Brachytheciastrum]]
|- id="key-3-72"
|72
|Plants on logs and soil in mesic to wet habitats.
|[[#key-3-73| > 73]]
|- id="key-3-73"
|73
|Leaves greater than 1 mm.
|[[Leptodictyum|Leptodictyum]]
|- id="key-3-73"
|73
|Leaves less than 1 mm.
|[[Amblystegium|Amblystegium]]
|- id="key-3-66"
|66
|Laminal cells linear, more than 10:1.
|[[#key-3-74| > 74]]
|- id="key-3-74"
|74
|Plants attached to rock in fast flowing streams and beside waterfalls.
|[[Rhynchostegium|Rhynchostegium]]
|- id="key-3-74"
|74
|Plants in various habitats but not on rock in fast flowing water.
|[[#key-3-75| > 75]]
|- id="key-3-75"
|75
|Plants terrestrial, large, coarse; stems erect, pinnate.
|[[#key-3-76| > 76]]
|- id="key-3-76"
|76
|Stem leaves ovate-lanceolate, acuminate to filiform, plicate; on litter in coniferous forests.
|[[Homalothecium|Homalothecium]]
|- id="key-3-76"
|76
|Stem leaves ovate-oblong, abruptly apiculate, not plicate; in lawns and gardens.
|[[Pseudoscleropodium|Pseudoscleropodium]]
|- id="key-3-75"
|75
|Plants various; stems variously branched, prostrate to ascending, if erect then in wetlands.
|[[#key-3-77| > 77]]
|- id="key-3-77"
|77
|Leaves plicate.
|[[#key-3-78| > 78]]
|- id="key-3-78"
|78
|Branches curved-ascending when dry.
|[[Homalothecium|Homalothecium]]
|- id="key-3-78"
|78
|Branches prostrate.
|[[#key-3-79| > 79]]
|- id="key-3-79"
|79
|Leaf margins entire to serrulate at apex; distal laminal cell walls firm; alar cells mostly differentiated, short-rectangular; plants soft.
|[[Brachytheciastrum|Brachytheciastrum]] / [[Brachythecium|Brachythecium]] / [[Sciuro-hypnum]] complex
|- id="key-3-79"
|79
|Leaf margins coarsely serrate at apex; distal laminal cell walls thick; alar cells well differentiated, quadrate; plants rigid.
|[[Palamocladium|Palamocladium]]
|- id="key-3-77"
|77
|Leaves not plicate.
|[[#key-3-80| > 80]]
|- id="key-3-80"
|80
|Plants on tree trunks; calyptrae sparsely hair y; setae rough; e United States.
|[[Homalotheciella|Homalotheciella]]
|- id="key-3-80"
|80
|Plants not on tree trunks except rarely at base; calyptrae naked; setae usually smooth, rarely rough; w North America.
|[[#key-3-81| > 81]]
|- id="key-3-81"
|81
|Stems terete-foliate, at least at apex; leaves broadly oblong to ovate, concave to cucullate.
|[[#key-3-82| > 82]]
|- id="key-3-82"
|82
|Leaf apices abruptly acuminate.
|[[#key-3-83| > 83]]
|- id="key-3-83"
|83
|Costae with 1+ terminal spines; w North America.
|[[Scleropodium|Scleropodium]]
|- id="key-3-83"
|83
|Costae without terminal spines; widespread.
|[[#key-3-84| > 84]]
|- id="key-3-84"
|84
|Leaf apices broader, twisted.
|[[Bryoandersonia|Bryoandersonia]]
|- id="key-3-84"
|84
|Leaf apices filiform, flat.
|[[Cirriphyllum|Cirriphyllum]]
|- id="key-3-82"
|82
|Leaf apices broadly acute to obtuse, sometimes with minute apiculus.
|[[#key-3-85| > 85]]
|- id="key-3-85"
|85
|Leaf apices with minute apiculus.
|[[#key-3-86| > 86]]
|- id="key-3-86"
|86
|Plants reddish; alar cells strongly inflated, walls thin.
|[[Sarmentypnum|Sarmentypnum]]
|- id="key-3-86"
|86
|Plants green to brownish; alar cells slightly inflated, walls thick.
|[[#key-3-87| > 87]]
|- id="key-3-87"
|87
|Leaves imbricate or slightly falcate-apiculate in Arctic species.
|[[Pseudocalliergon|Pseudocalliergon]]
|- id="key-3-87"
|87
|Leaves falcate.
|[[Loeskypnum|Loeskypnum]]
|- id="key-3-85"
|85
|Leaf apices not apiculate.
|[[#key-3-88| > 88]]
|- id="key-3-88"
|88
|Leaf apices broadly acute; on moist rock and soil; Pacific coast.
|[[Scleropodium|Scleropodium]]
|- id="key-3-88"
|88
|Leaf apices obtuse; in fens and swamps; widespread.
|[[#key-3-89| > 89]]
|- id="key-3-89"
|89
|Plants slender, wormlike, unbranched; leaves tightly imbricate.
|[[Pseudocalliergon|Pseudocalliergon]]
|- id="key-3-89"
|89
|Plants robust, branched; leaves loosely imbricate at least proximally.
|[[Calliergon|Calliergon]]
|- id="key-3-81"
|81
|Stems with spreading leaves; leaves lanceolate, not or scarcely concave.
|[[#key-3-90| > 90]]
|- id="key-3-90"
|90
|Branch leaf apical laminal cells 1/2 length of medial cells.
|[[Eurhynchiastrum|Eurhynchiastrum]]
|- id="key-3-90"
|90
|Branch leaf apical laminal cells scarcely shorter than medial cells.
|[[#key-3-91| > 91]]
|- id="key-3-91"
|91
|Leaf apices twisted; stems often complanate-foliate.
|[[Rhynchostegium|Rhynchostegium]]
|- id="key-3-91"
|91
|Leaf apices flat; stems rarely complanate-foliate.
|[[#key-3-92| > 92]]
|- id="key-3-92"
|92
|Leaf apices channeled; bases concave, insertions narrow.
|[[#key-3-93| > 93]]
|- id="key-3-93"
|93
|Leaves more than 1.6 mm, falcate to straight.
|[[Drepanocladus|Drepanocladus]]
|- id="key-3-93"
|93
|Leaves less than 1.7 mm, recurved to squarrose.
|[[#key-3-94| > 94]]
|- id="key-3-94"
|94
|Largest alar cells 10 – 19 µm wide; sexual condition dioicous.
|[[Campyliadelphus|Campyliadelphus]]
|- id="key-3-94"
|94
|Largest alar cells 18 – 25 µm wide; sexual condition autoicous.
|[[Pseudocampylium|Pseudocampylium]]
|- id="key-3-92"
|92
|Leaf apices not channeled; bases not concave, insertions not narrow.
|[[#key-3-95| > 95]]
|- id="key-3-95"
|95
|Alar cells many, quadrate, with more on one side of costa than the other, collenchymatous; s Florida.
|[[Entodontopsis|Entodontopsis]]
|- id="key-3-95"
|95
|Alar cells few, quadrate to rectangular, symmetrically arranged, not collenchymatous; widespread.
|[[#key-3-96| > 96]]
|- id="key-3-96"
|96
|Stem and branch leaves strongly differentiated; opercula long-rostrate.
|[[Kindbergia|Kindbergia]]
|- id="key-3-96"
|96
|Stem and branch leaves scarcely differentiated; opercula conic to apiculate.
|[[#key-3-97| > 97]]
|- id="key-3-97"
|97
|Costae ending well below leaf apex.
|[[#key-3-98| > 98]]
|- id="key-3-98"
|98
|Leaves wide-spreading; margins entire; stems complanate-foliate; in wet habitats.
|[[Leptodictyum|Leptodictyum]]
|- id="key-3-98"
|98
|Leaves erect to spreading; margins serrulate, rarely entire; stems not complanat e-foliate; in various habitats.
|[[Brachytheciastrum|Brachytheciastrum]] / [[Brachythecium|Brachythecium]]
|- id="key-3-97"
|97
|Costae percurrent or nearly so.
|[[#key-3-99| > 99]]
|- id="key-3-99"
|99
|Costae indistinct at mid leaf, not toothed; setae smooth; propagula 1-seriate, often on distal abaxial costa.
|[[Conardia|Conardia]]
|- id="key-3-99"
|99
|Costae distinct throughout, toothed on distal abaxial surface; setae rough; propagula absent.
|[[Brachytheciastrum|Brachytheciastrum]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-4">Subkey D</h3>
{| class="wikitable fna-keytable"
|- id="key-4-1"
|1
|Capsules large, sessile, asymmetric.
|[[Diphyscium|Diphyscium]]
|- id="key-4-1"
|1
|Capsules smaller, usually exserted, symmetric.
|[[#key-4-2| > 2]]
|- id="key-4-2"
|2
|Costae with abaxial surface ridged.
|[[#key-4-3| > 3]]
|- id="key-4-3"
|3
|Laminal cells rounded-oblate, less than 3:1.
|[[Grimmia|Grimmia]]
|- id="key-4-3"
|3
|Laminal cells long-rectangular, more than 5:1.
|[[Dicranum|Dicranum]]
|- id="key-4-2"
|2
|Costae with abaxial surface smooth or toothed, not ridged.
|[[#key-4-4| > 4]]
|- id="key-4-4"
|4
|Rhizoids in conspicuous clusters, obscuring stem.
|[[#key-4-5| > 5]]
|- id="key-4-5"
|5
|Laminal cells strongly 1-papillose on both surfaces.
|[[Aulacomnium|Aulacomnium]]
|- id="key-4-5"
|5
|Laminal cells smooth or prorulose.
|[[#key-4-6| > 6]]
|- id="key-4-6"
|6
|Leaves narrowly lanceolate from ovate base.
|[[Anacolia|Anacolia]]
|- id="key-4-6"
|6
|Leaves ovate to broadly elliptic.
|[[#key-4-7| > 7]]
|- id="key-4-7"
|7
|Rhizoidal (macronematal) initials in longitudinal rows; endostome segments fused into dome.
|[[Cinclidium|Cinclidium]]
|- id="key-4-7"
|7
|Rhizoidal initials not in longitudinal rows; endostome segments free.
|[[Rhizomnium|Rhizomnium]]
|- id="key-4-4"
|4
|Rhizoids inconspicuous or if conspicuous, never obscuring stem.
|[[#key-4-8| > 8]]
|- id="key-4-8"
|8
|Plants blackish, on wet rock usually near streams or sea; propagula absent.
|[[#key-4-9| > 9]]
|- id="key-4-9"
|9
|Leaf bases with submarginal band of elongate cells.
|[[Scouleria|Scouleria]]
|- id="key-4-9"
|9
|Leaf bases without differentiated submarginal cells.
|[[#key-4-10| > 10]]
|- id="key-4-10"
|10
|Leaf margins plane to recurved.
|[[Schistidium|Schistidium]]
|- id="key-4-10"
|10
|Leaf margins incurved.
|[[Grimmia|Grimmia]]
|- id="key-4-8"
|8
|Plants greenish, in various habitats, rarely on wet rock by streams; propagula present or absent.
|[[#key-4-11| > 11]]
|- id="key-4-11"
|11
|Hyaline basal cells extending up margins farther than at costa, forming V -shaped region.
|[[#key-4-12| > 12]]
|- id="key-4-12"
|12
|Distal laminal cells bulging but not papillose.
|[[Luisierella|Luisierella]]
|- id="key-4-12"
|12
|Distal laminal cells multipapillose.
|[[#key-4-13| > 13]]
|- id="key-4-13"
|13
|Leaves squarrose-recurved from erect base when moist; leaf margins serrulate distally; sporophytes lateral.
|[[Pleurochaete|Pleurochaete]]
|- id="key-4-13"
|13
|Leaves erect-spreading to spreading from erect base when moist; leaf margins entire to notched; sporophytes terminal.
|[[Tortella|Tortella]]
|- id="key-4-11"
|11
|Hyaline basal cells if present extending ± equally up margins and costa, or farther up costa.
|[[#key-4-14| > 14]]
|- id="key-4-14"
|14
|Plants glaucous, bluish green; leaves narrowly lanceolate.
|[[Saelania|Saelania]]
|- id="key-4-14"
|14
|Plants usually not glaucous or bluish, if so then leaves not lanceolate.
|[[#key-4-15| > 15]]
|- id="key-4-15"
|15
|Leaves unbordered, or if bordered then by only 1 row (or several poorly defined rows) of somewhat elongate cells, or by short cells.
|[[#key-4-16| > 16]]
|- id="key-4-16"
|16
|Leaf margins with single teeth or entire.
|[[#key-4-17| > 17]]
|- id="key-4-17"
|17
|Laminal cells smooth or papillose, not bulging, or if bulging then papillose.
|[[#key-5|Subkey E]]
|- id="key-4-17"
|17
|Laminal cells strongly bulging on one or both surfaces, not papillose.
|[[#key-4-18| > 18]]
|- id="key-4-18"
|18
|Leaf laminae 2-stratose.
|[[Timmiella|Timmiella]]
|- id="key-4-18"
|18
|Leaf laminae 1-stratose.
|[[#key-4-19| > 19]]
|- id="key-4-19"
|19
|Leaf bases sheathing.
|[[Timmia|Timmia]]
|- id="key-4-19"
|19
|Leaf bases not sheathing.
|[[#key-4-20| > 20]]
|- id="key-4-20"
|20
|Distal laminal cells bulging on both surfaces; calyptrae mitrate; Arctic and n North America11-1. Bryobrittonia, v. 27, p. 171
|[[#key-4-20| > 20]]
|- id="key-4-20"
|20
|Distal laminal cells bulging only on adaxial surface; calyptrae cucullate; temperate distribution.
|[[Hyophiladelphus|Hyophiladelphus]]
|- id="key-4-16"
|16
|Leaf margins with paired teeth.
|[[#key-4-21| > 21]]
|- id="key-4-21"
|21
|Leaf bases with abruptly differentiated unpigmented cells (cancellinae); propagula on distal costa.
|[[Syrrhopodon|Syrrhopodon]]
|- id="key-4-21"
|21
|Leaf bases without cancellinae; propagula absent.
|[[#key-4-22| > 22]]
|- id="key-4-22"
|22
|Laminal cells smooth.
|[[#key-4-23| > 23]]
|- id="key-4-23"
|23
|Leaves elliptic to ovate-elliptic.
|[[Mnium|Mnium]]
|- id="key-4-23"
|23
|Leaves linear-lanceolate.
|[[Pyrrhobryum|Pyrrhobryum]]
|- id="key-4-22"
|22
|Laminal cells prorulose or with fine cuticular ridges.
|[[#key-4-24| > 24]]
|- id="key-4-24"
|24
|Distal laminal cells with cuticular ridges; stems t riangular in transverse section.
|[[Plagiopus|Plagiopus]]
|- id="key-4-24"
|24
|Distal laminal cells prorulose; stems round in transverse section.
|[[#key-4-25| > 25]]
|- id="key-4-25"
|25
|Leaves crispate when dry.
|[[Bartramia|Bartramia]]
|- id="key-4-25"
|25
|Leaves straight when dry.
|[[Philonotis|Philonotis]]
|- id="key-4-15"
|15
|Leaves bordered by 2+ rows of elongate cells.
|[[#key-4-26| > 26]]
|- id="key-4-26"
|26
|Leaf margins entire.
|[[#key-4-27| > 27]]
|- id="key-4-27"
|27
|Laminal cells 1 – 2:1.
|[[#key-4-28| > 28]]
|- id="key-4-28"
|28
|Rhizoidal (macronematal) initials in longitudinal rows; endostome segments fused into dome.
|[[Cinclidium|Cinclidium]]
|- id="key-4-28"
|28
|Rhizoidal initials not in longitudinal rows; endostome segments free.
|[[#key-4-29| > 29]]
|- id="key-4-29"
|29
|Leaves ovate or broadly elliptic; border 1-stratose; stems blackish; stomata superficial.
|[[Cyrtomnium|Cyrtomnium]]
|- id="key-4-29"
|29
|Leaves obovate or elliptic, occasionally orbicular; border thickness various; stems usually reddish; stomata immersed.
|[[Rhizomnium|Rhizomnium]]
|- id="key-4-27"
|27
|Most laminal cells longer than 3:1.
|[[#key-4-30| > 30]]
|- id="key-4-30"
|30
|Laminal cells in oblique rows; leaf apices rounded-obtuse, usually apiculate.
|[[Pseudobryum|Pseudobryum]]
|- id="key-4-30"
|30
|Laminal cells not in obvious rows; leaf apices various.
|[[#key-4-31| > 31]]
|- id="key-4-31"
|31
|Distal laminal cells 3 – 6:1, longer than proximal cells; leaves imbricate, not contorted or twisted when dry; border cells 1-stratose.
|[[#key-4-32| > 32]]
|- id="key-4-32"
|32
|Plants mostly less than 1 cm; leaves less than 2.5 mm.
|[[Gemmabryum|Gemmabryum]]
|- id="key-4-32"
|32
|Plants mostly 1 – 3 cm; leaves 1 – 3.5 mm.
|[[Imbribryum|Imbribryum]]
|- id="key-4-31"
|31
|Distal laminal cells 2 – 4:1, similar in length to proximal cells; leaves twisted to contorted when dry; border cells 1-or 2-stratose.
|[[#key-4-33| > 33]]
|- id="key-4-33"
|33
|Leaves ovate-lanceolate to ovate; border cells 1-or 2-stratose.
|[[Ptychostomum|Ptychostomum]]
|- id="key-4-33"
|33
|Leaves ovate to obovate; border cells 1-stratose.
|[[Rosulabryum|Rosulabryum]]
|- id="key-4-26"
|26
|Leaf margins toothed, sometimes obscurely so.
|[[#key-4-34| > 34]]
|- id="key-4-34"
|34
|Leaf bases expanded, with many abruptly hyaline cells.
|[[Syrrhopodon|Syrrhopodon]]
|- id="key-4-34"
|34
|Leaf bases not expanded, without hyaline cells.
|[[#key-4-35| > 35]]
|- id="key-4-35"
|35
|Leaf marginal teeth paired.
|[[#key-4-36| > 36]]
|- id="key-4-36"
|36
|Laminal cells mammillose.
|[[Trachycystis|Trachycystis]]
|- id="key-4-36"
|36
|Laminal cells not mammillose.
|[[#key-4-37| > 37]]
|- id="key-4-37"
|37
|Some leaves with low, inconspicuous lamellae; costal stereid bands 2; exostome teeth 32, attached at apices to tympanum.
|[[Atrichum|Atrichum]]
|- id="key-4-37"
|37
|Lamellae absent; costal stereid band 1 or absent; exostome teeth 16, free.
|[[Mnium|Mnium]]
|- id="key-4-35"
|35
|Leaf marginal teeth single.
|[[#key-4-38| > 38]]
|- id="key-4-38"
|38
|Leaves rugose when dry or moist; restricted to Pacific Northwest.
|[[Roellobryon|Roellobryon]]
|- id="key-4-38"
|38
|Leaves usually flat when moist, contorted but not rugose when dry; widespread.
|[[#key-4-39| > 39]]
|- id="key-4-39"
|39
|Laminal cells shorter than 2:1.
|[[Plagiomnium|Plagiomnium]]
|- id="key-4-39"
|39
|Laminal cells 3+:1.
|[[#key-4-40| > 40]]
|- id="key-4-40"
|40
|Stems rosulate-foliate, erect from horizontal underground stem; sporophytes often clustered.
|[[Rhodobryum|Rhodobryum]]
|- id="key-4-40"
|40
|Stems foliate throughout, without rhizomelike connections between erect stems; sporophytes not clustered.
|[[#key-4-41| > 41]]
|- id="key-4-41"
|41
|Laminal cells in oblique rows; leaf apices rounded-obtuse, usually apiculate.
|[[Pseudobryum|Pseudobryum]]
|- id="key-4-41"
|41
|Laminal cells not in obvious rows; leaf apices broadly acute to acuminate.
|[[#key-4-42| > 42]]
|- id="key-4-42"
|42
|Plants roselike with distinctive head of terminal leaves.
|[[#key-4-43| > 43]]
|- id="key-4-43"
|43
|Capsules erect, symmetric; endostome basal membrane high, segments absent or rudimentary, cilia absent.
|[[Brachymenium|Brachymenium]]
|- id="key-4-43"
|43
|Capsules inclined, asymmetric; endostome basal membrane keeled, segments keeled, perforate, cilia usually present.
|[[Rosulabryum|Rosulabryum]]
|- id="key-4-42"
|42
|Plants with leaves evenly arranged along stem or bulbiform.
|[[#key-4-44| > 44]]
|- id="key-4-44"
|44
|Distal laminal cells 3 – 6:1, longer than proximal cells; leaves imbricate, not contorted or twisted when dry; border cells 1-stratose.
|[[#key-4-45| > 45]]
|- id="key-4-45"
|45
|Plants mostly less than 1 cm; leaves less than 2.5 mm.
|[[Gemmabryum|Gemmabryum]]
|- id="key-4-45"
|45
|Plants mostly 1 – 3 cm; leaves 1 – 3.5 mm.
|[[Imbribryum|Imbribryum]]
|- id="key-4-44"
|44
|Distal laminal cells 2 – 4:1, similar in length to proximal cells; leaves twisted to contorted when dry; border cells 1-or 2-stratose.
|[[#key-4-46| > 46]]
|- id="key-4-46"
|46
|Leaves ovate-lanceolate to ovate; border cells 1-or 2-stratose.
|[[Ptychostomum|Ptychostomum]]
|- id="key-4-46"
|46
|Leaves ovate to obovate; border cells 1-stratose.
|[[Rosulabryum|Rosulabryum]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-5">Subkey E</h3>
{| class="wikitable fna-keytable"
|- id="key-5-1"
|1
|Leaf bases abruptly expanded, sheathing.
|[[#key-5-2| > 2]]
|- id="key-5-2"
|2
|Laminal cells papillose (at least on sheath) or prorulose.
|[[#key-5-3| > 3]]
|- id="key-5-3"
|3
|Laminal cells papillose over lumina.
|[[Timmia|Timmia]]
|- id="key-5-3"
|3
|Laminal cells prorulose.
|[[Bartramia|Bartramia]]
|- id="key-5-2"
|2
|Laminal cells smooth.
|[[#key-5-4| > 4]]
|- id="key-5-4"
|4
|Distal laminal cells quadrate.
|[[#key-5-5| > 5]]
|- id="key-5-5"
|5
|Capsules inclined, asymmetric, strumose; widespread.
|[[Oncophorus|Oncophorus]]
|- id="key-5-5"
|5
|Capsules erect, symmetric, not strumose; restricted to sw United States.
|[[Symblepharis|Symblepharis]]
|- id="key-5-4"
|4
|Distal laminal cells short-rectangular.
|[[#key-5-6| > 6]]
|- id="key-5-6"
|6
|Leaf awns roughened throughout by projecting cell ends.
|[[Trichodon|Trichodon]]
|- id="key-5-6"
|6
|Leaf awns smooth or only rough at apex.
|[[#key-5-7| > 7]]
|- id="key-5-7"
|7
|Capsule neck as long as or longer than urn.
|[[Trematodon|Trematodon]]
|- id="key-5-7"
|7
|Capsule neck much shorter than urn.
|[[#key-5-8| > 8]]
|- id="key-5-8"
|8
|Capsules inclined, oblong, smooth or furrowed, if erect then furrowed; peristome teeth flat, split mid tooth, vertically pitted.
|[[Dicranella|Dicranella]]
|- id="key-5-8"
|8
|Capsules erect, cylindric, smooth; peristome teeth irregularly perforate or deeply cleft into teret e, sometimes filiform divisions
|[[#key-5-1| > 1]]
|- id="key-5-1"
|1
|Leaf bases not or gradually expanded, rarely sheathing.
|[[#key-5-9| > 9]]
|- id="key-5-9"
|9
|Alar cells enlarged, pigmented, or inflated.
|[[#key-5-10| > 10]]
|- id="key-5-10"
|10
|Distal and medial laminal cells with coarse, irregular cuticular ridges, resembling papillae in transverse section; capsules cylindric, smooth, erect.
|[[#key-5-11| > 11]]
|- id="key-5-11"
|11
|Leaves with clusters of spheric propagula at apex; leaf margins 2-stratose.
|[[Grimmia|Grimmia]]
|- id="key-5-11"
|11
|Leaves without propagula; leaf margins 1-stratose.
|[[Dicranoweisia|Dicranoweisia]]
|- id="key-5-10"
|10
|Laminal cells without cuticular ridges; capsules various.
|[[#key-5-12| > 12]]
|- id="key-5-12"
|12
|Costal stereid bands 2.
|[[Dicranum|Dicranum]]
|- id="key-5-12"
|12
|Costal stereid bands absent.
|[[#key-5-13| > 13]]
|- id="key-5-13"
|13
|Capsules curved, strumose; on alpine rock.
|[[Kiaeria|Kiaeria]]
|- id="key-5-13"
|13
|Capsules straight, not strumose; widespread.
|[[#key-5-14| > 14]]
|- id="key-5-14"
|14
|Capsules cylindric; usually terrestrial or on tree trunks, rarely on rock.
|[[Dicranum|Dicranum]]
|- id="key-5-14"
|14
|Capsules short, obovoid to pyriform; on rock.
|[[#key-5-15| > 15]]
|- id="key-5-15"
|15
|Capsules smooth when dry; peristome papillose.
|[[Blindia|Blindia]]
|- id="key-5-15"
|15
|Capsules ribbed when dry; peristome vertically pitted-striolate proximally.
|[[Arctoa|Arctoa]]
|- id="key-5-9"
|9
|Alar cells scarcely differentiated.
|[[#key-5-16| > 16]]
|- id="key-5-16"
|16
|Laminal cells smooth.
|[[#key-5-17| > 17]]
|- id="key-5-17"
|17
|Asexual propagula borne on leaf surfaces.
|[[Rhachithecium|Rhachithecium]]
|- id="key-5-17"
|17
|Asexual propagula absent, axillary, or on leaf apices or specialized structures.
|[[#key-5-18| > 18]]
|- id="key-5-18"
|18
|Leaves ovate to obovate; apices broadly obtuse; costae ending before apex.
|[[#key-5-19| > 19]]
|- id="key-5-19"
|19
|Leaf apices cucullate.
|[[Globulinella|Globulinella]]
|- id="key-5-19"
|19
|Leaf apices not cucullate.
|[[#key-5-20| > 20]]
|- id="key-5-20"
|20
|Propagula large, multicellular, in leaf axils; leaves obovate; margins ciliate basally.
|[[Oedipodium|Oedipodium]]
|- id="key-5-20"
|20
|Axillary propagula absent; leaves ovate to spatulate; margins eciliate.
|[[#key-5-21| > 21]]
|- id="key-5-21"
|21
|Plants small, bulbiform, on dry soil; leaves concave, imbricate.
|[[Stegonia|Stegonia]]
|- id="key-5-21"
|21
|Plants small to medium-sized, never bulbiform, on moist soil; leaves flat to concave, mostly not imbricate.
|[[#key-5-22| > 22]]
|- id="key-5-22"
|22
|Laminal cells short-rectangular, lax, walls thin; capsules erect.
|[[#key-5-23| > 23]]
|- id="key-5-23"
|23
|Apical marginal laminal cells short-rhombic, oblong-hexagonal internally; capsule neck not distinct; s United States.
|[[Splachnobryum|Splachnobryum]]
|- id="key-5-23"
|23
|Apical marginal laminal cells laxly rectangular, similar to internal ones; capsule neck well differentiated; n North America.
|[[Tayloria|Tayloria]]
|- id="key-5-22"
|22
|Laminal cells long-hexagonal, walls firm; capsules inclined to horizontal.
|[[#key-5-24| > 24]]
|- id="key-5-24"
|24
|Plants whitish; stems terete-foliate; distal laminal cells 7 – 9:1.
|[[Anomobryum|Anomobryum]]
|- id="key-5-24"
|24
|Plants reddish or green; stems not terete-folia te; distal laminal cells 2 – 6:1.
|[[Bryum|Bryum]]
|- id="key-5-18"
|18
|Leaves linear, ovate-lanceolate, ligulate to ovate; apices acuminate to acute or awned; costae ending below apex to excurrent.
|[[#key-5-25| > 25]]
|- id="key-5-25"
|25
|Leaves lanceolate to linear.
|[[#key-5-26| > 26]]
|- id="key-5-26"
|26
|Leaves conspicuously 4-ranked.
|[[Conostomum|Conostomum]]
|- id="key-5-26"
|26
|Leaves not conspicuously ranked (if 3-ranked see 35 – 3. Meesia (in part), v. 28, p. 32).
|[[#key-6|Subkey F]]
|- id="key-5-25"
|25
|Leaves oblong, lingulate to ovate.
|[[#key-5-27| > 27]]
|- id="key-5-27"
|27
|Laminal cells rounded to quadrate, ± isodiametric.
|[[#key-5-28| > 28]]
|- id="key-5-28"
|28
|Leaf bases with abruptly differentiated, hyaline cells (cancellinae); apices often with propagula.
|[[Calymperes|Calymperes]]
|- id="key-5-28"
|28
|Leaf bases without cancellinae although sometimes gradually hyaline; apices without propagula.
|[[#key-5-29| > 29]]
|- id="key-5-29"
|29
|Costae subpercurrent; apices broadly acute or obtuse to rarely mucronate.
|[[#key-5-30| > 30]]
|- id="key-5-30"
|30
|Peristome teeth 4; propagula cups bo rne on apices of sterile shoots
|[[#key-5-30| > 30]]
|- id="key-5-30"
|30
|Peristome teeth 16; propagula cups absent.
|[[#key-5-31| > 31]]
|- id="key-5-31"
|31
|Leaves homomallous, broadly oblong to oblong-ovate; apices subacute to obtuse.
|[[Arrhenopterum|Arrhenopterum]]
|- id="key-5-31"
|31
|Leaves not homomallous, oblong to lanceolate; apices mucronate to acuminate.
|[[#key-5-32| > 32]]
|- id="key-5-32"
|32
|Leaves broadly to narrowly lanceolate; peristome double.
|[[Meesia|Meesia]]
|- id="key-5-32"
|32
|Leaves broadly oblong to spatulate; peristome single.
|[[#key-5-33| > 33]]
|- id="key-5-33"
|33
|Costal stereid band 1.
|[[Scopelophila|Scopelophila]]
|- id="key-5-33"
|33
|Costal stereid bands 2.
|[[Barbula|Barbula]]
|- id="key-5-29"
|29
|Costae excurrent to ending in cusp; apices cuspidate to piliferous.
|[[#key-5-34| > 34]]
|- id="key-5-34"
|34
|Leaf apices piliferous.
|[[Tortula|Tortula]]
|- id="key-5-34"
|34
|Leaf apices cuspidate, apiculate, or acuminate.
|[[#key-5-35| > 35]]
|- id="key-5-35"
|35
|Leaves obovate to elliptic; apices apiculate [of 1( – 3) thick-walled cells] ; rhizoidal tubers present.
|[[Chenia|Chenia]]
|- id="key-5-35"
|35
|Leaves ovate to spathulate; apices acute, mucronate, or acuminate; rhizoidal tubers absent.
|[[#key-5-36| > 36]]
|- id="key-5-36"
|36
|Distal marginal laminal cells differentiated from inner cells.
|[[Microbryum|Microbryum]]
|- id="key-5-36"
|36
|Distal marginal laminal cells similar to inner cells.
|[[#key-5-37| > 37]]
|- id="key-5-37"
|37
|Distal leaf margins dentate; marginal cells smaller, walls thicker than inner cells.
|[[Hennediella|Hennediella]]
|- id="key-5-37"
|37
|Distal leaf margins entire; marginal cells larger, walls thinner than inner cells.
|[[Crumia|Crumia]]
|- id="key-5-27"
|27
|Laminal cells short-rectangular to linear.
|[[#key-5-38| > 38]]
|- id="key-5-38"
|38
|Plants filiform; stems julaceous (if costa not excurrent see also 42 – 1. Anomobryum (in part) , v. 28, p. 120).
|[[Aongstroemia|Aongstroemia]]
|- id="key-5-38"
|38
|Plants coarser; stems not julaceous.
|[[#key-5-39| > 39]]
|- id="key-5-39"
|39
|Laminal cells (5 – )7+:1; leaves generally lanceolate.
|[[Pohlia|Pohlia]]
|- id="key-5-39"
|39
|Laminal cells (3 – )4:1 or shorter; leaves generally ovate-lanceolate.
|[[#key-5-40| > 40]]
|- id="key-5-40"
|40
|Capsules horizontal to pendulous.
|[[#key-5-41| > 41]]
|- id="key-5-41"
|41
|Capsules curved, asymmetric, pendulous.
|[[#key-5-42| > 42]]
|- id="key-5-42"
|42
|Exostome teeth longer than and opposite to endostome segments.
|[[Funaria|Funaria]]
|- id="key-5-42"
|42
|Exostome teeth either reduced or alternate to endostome segments.
|[[Plagiobryum|Plagiobryum]]
|- id="key-5-41"
|41
|Capsules straight, symmetric, inclined to horizontal.
|[[#key-5-43| > 43]]
|- id="key-5-43"
|43
|Gametophores much reduced; stems to 0.2 mm; leaves less than 1 mm; costae nearly absent; capsules subspheric to globose, less than 1 mm; stomata absent; endostome fused to exostome, cilia absent.
|[[Discelium|Discelium]]
|- id="key-5-43"
|43
|Gametophores not reduced; stems and leaves larger; costae present; capsules cylindric to ovate, usually greater than 1 mm; stomata present; endostome free of exostome, cilia or endostome segments mostly present.
|[[#key-5-44| > 44]]
|- id="key-5-44"
|44
|Capsules short-pyriform to ovate, neck short; sporophytes lateral; peristome with endostome only.
|[[Haplodontium|Haplodontium]]
|- id="key-5-44"
|44
|Capsules pyriform, neck long; sporophytes terminal; peristome with endostome and exostome.
|[[#key-5-45| > 45]]
|- id="key-5-45"
|45
|Rhizoidal tubers small, pyriform, brown, 40 – 60 µm; laminal cells less than 15 µm wide; alar cells quadrate.
|[[Gemmabryum|Gemmabryum]]
|- id="key-5-45"
|45
|Rhizoidal tubers large, spheric, red, often greater than 200 µm, or absent; laminal cells typically greater than 20 µm wide; alar cells not quadrate.
|[[Plagiobryoides|Plagiobryoides]]
|- id="key-5-40"
|40
|Capsules erect.
|[[#key-5-46| > 46]]
|- id="key-5-46"
|46
|Peristome absent.
|[[#key-5-47| > 47]]
|- id="key-5-47"
|47
|Calyptrae 4-angled, sheathing entire capsule until after dehiscence.
|[[Pyramidula|Pyramidula]]
|- id="key-5-47"
|47
|Calyptrae not angled, not sheathing or persistent.
|[[#key-5-48| > 48]]
|- id="key-5-48"
|48
|Capsules subcylindric or narrowly pyriform; annuli absent; exothecial cells oblong to oblong-linear; calyptrae inflated-cucullate.
|[[Entosthodon|Entosthodon]]
|- id="key-5-48"
|48
|Capsules urceolate to broadly pyriform; annuli present; exothecial cells irregularly hexagonal; calyptrae inflated-mitrate.
|[[Physcomitrium|Physcomitrium]]
|- id="key-5-46"
|46
|Peristome present.
|[[#key-5-49| > 49]]
|- id="key-5-49"
|49
|Peristome of endostome only, without center line on external surface.
|[[#key-5-50| > 50]]
|- id="key-5-50"
|50
|Leaf margins entire.
|[[Haplodontium|Haplodontium]]
|- id="key-5-50"
|50
|Leaf margins denticulate.
|[[Mielichhoferia|Mielichhoferia]]
|- id="key-5-49"
|49
|Peristome double or of exostome only, with center line on external surface.
|[[#key-5-51| > 51]]
|- id="key-5-51"
|51
|Capsule neck scarcely differentiated.
|[[#key-5-52| > 52]]
|- id="key-5-52"
|52
|Plants of British Columbia (50° N) and south.
|[[Entosthodon|Entosthodon]]
|- id="key-5-52"
|52
|Plants of arctic tundra.
|[[Funaria|Funaria]]
|- id="key-5-51"
|51
|Capsule neck well differentiated.
|[[#key-5-53| > 53]]
|- id="key-5-53"
|53
|Capsule urns black, hypophyses sometimes yellow.
|[[Tetraplodon|Tetraplodon]]
|- id="key-5-53"
|53
|Capsule urns and hypophyses green to brown.
|[[#key-5-54| > 54]]
|- id="key-5-54"
|54
|Setae brownish, stout to slender; costae ending below apex; w, n North America.
|[[Tayloria|Tayloria]]
|- id="key-5-54"
|54
|Setae pale greenish white, slender; costae filling acumen; e North America.
|[[Splachnum|Splachnum]]
|- id="key-5-16"
|16
|Laminal cells papillose or prorulose.
|[[#key-5-55| > 55]]
|- id="key-5-55"
|55
|Leaves 2-stratose throughout, ligulate to oblong; apices obtuse; perichaetial leaves long-awned.
|[[Diphyscium|Diphyscium]]
|- id="key-5-55"
|55
|Leaves 1-stratose, or if 2-stratose then not ligulate to oblong; apices acuminate, acute, or obtuse; perichaetial leaves not so differentiated.
|[[#key-5-56| > 56]]
|- id="key-5-56"
|56
|Laminal cells rectangular, prorulose; capsules globose, rugulose to furrowed when dry.
|[[#key-5-57| > 57]]
|- id="key-5-57"
|57
|Leaves strongly ranked.
|[[Conostomum|Conostomum]]
|- id="key-5-57"
|57
|Leaves not conspicuously ranked.
|[[#key-5-58| > 58]]
|- id="key-5-58"
|58
|Capsules erect, or if pendent then from curvature of seta, symmetric, rugulose when dry; peristome reduced to low membrane.
|[[Philonotis|Philonotis]]
|- id="key-5-58"
|58
|Capsules strongly inclined, asymmetric, furrowed; peristome more developed.
|[[#key-5-59| > 59]]
|- id="key-5-59"
|59
|Leaves 2-stratose at least at margins; on banks and cliffs in mesic habitats; innovative branches absent.
|[[Bartramia|Bartramia]]
|- id="key-5-59"
|59
|Leaves 1-stratose; on soil and rock in at least periodically wet habitats; innovative branches often present beneath inflorescences.
|[[Philonotis|Philonotis]]
|- id="key-5-56"
|56
|Laminal cells rounded-quadrate, 1 – multipapillose; capsules ovate to cylindric, smooth or furrowed.
|[[#key-5-60| > 60]]
|- id="key-5-60"
|60
|Laminal cells appearing papillose from slightly thickened walls between cells (not prorulose).
|[[#key-5-61| > 61]]
|- id="key-5-61"
|61
|Leaves erect, straight to curved; capsules immersed to short-exserted, ovate-cylindric; on rock.
|[[Grimmia|Grimmia]]
|- id="key-5-61"
|61
|Leaves crispate when dry; capsules long-exserted, cylindric; usually on logs.
|[[Dicranoweisia|Dicranoweisia]]
|- id="key-5-60"
|60
|Laminal cells papillose over lumina.
|[[#key-5-62| > 62]]
|- id="key-5-62"
|62
|Laminal cells collenchymatous, stellate.
|[[#key-5-63| > 63]]
|- id="key-5-63"
|63
|Laminal cells multipapillose; leaves recurved.
|[[Didymodon|Didymodon]]
|- id="key-5-63"
|63
|Laminal cells 1-papillose; leaves not recurved.
|[[Aulacomnium|Aulacomnium]]
|- id="key-5-62"
|62
|Laminal cells not collenchymatous, or if so, not stellate.
|[[#key-5-64| > 64]]
|- id="key-5-64"
|64
|Leaves with abruptly differentiated hyaline cells occupying most of base (cancellinae), and with intramarginal border of elongate cells (teniolae), at least in proximal part of leaf; propagula usuall y present on leaf apex
|[[#key-5-64| > 64]]
|- id="key-5-64"
|64
|Leaves without cancellinae, or if present then never with teniolae; propagula never on leaf apices but sometimes elsewhere on leaves or in axils.
|[[#key-5-65| > 65]]
|- id="key-5-65"
|65
|Plants with propagula borne terminally on spec ialized stalks from stem apices.
|[[Aulacomnium|Aulacomnium]]
|- id="key-5-65"
|65
|Plants with or without various means of asexual reproduction but these never borne on stalks from stem apices.
|[[#key-5-66| > 66]]
|- id="key-5-66"
|66
|Plants on tree trunks or bare rock; capsules immersed to short-exserted, often ribbed.
|[[#key-5-67| > 67]]
|- id="key-5-67"
|67
|Calyptrae cucullate, not plicate, naked; on wet rock.
|[[Amphidium|Amphidium]]
|- id="key-5-67"
|67
|Calyptrae mitrate, plicate, usually hairy; on tree trunks and dry rock.
|[[#key-5-68| > 68]]
|- id="key-5-68"
|68
|Leaves usually little altered when dry; basal marginal laminal cells not differentiated; stomata immersed or superficial; caps ules immersed to short-exserted.
|[[Orthotrichum|Orthotrichum]]
|- id="key-5-68"
|68
|Leaves usually crispate to contorted when dry; basal marginal laminal cells with thickened transverse walls; stomata superficial; capsules short-exserted.
|[[Ulota|Ulota]]
|- id="key-5-66"
|66
|Plants usually on soil, if on rock or trees then capsules long-exserted and mostly unribbed (or plants sterile).
|[[#key-5-69| > 69]]
|- id="key-5-69"
|69
|Costal stereid bands not differentiated.
|[[#key-5-70| > 70]]
|- id="key-5-70"
|70
|Laminal cell papillae C -shaped; leaves broadly spatulate.
|[[Gymnostomiella|Gymnostomiella]]
|- id="key-5-70"
|70
|Laminal cell papillae simple, conic; leaves not broadly spatulate.
|[[#key-5-71| > 71]]
|- id="key-5-71"
|71
|Distal laminal cell papillae 4 – 7, conic.
|[[Zygodon|Zygodon]]
|- id="key-5-71"
|71
|Distal laminal cell papillae 3 or fewer, simple to branched.
|[[#key-5-72| > 72]]
|- id="key-5-72"
|72
|Leaves less than 0.6 mm, ligulate; apices rounded-obtuse; annuli of 2 or 3 rows of well-differentiated cells.
|[[Gyroweisia|Gyroweisia]]
|- id="key-5-72"
|72
|Leaves more than (0.7 – )1.5 mm, lanceolate to ovate; apices acuminate to obtuse; annuli poorly differentiated.
|[[#key-5-73| > 73]]
|- id="key-5-73"
|73
|Leaves usually little altered when dry; basal marginal laminal cells not differentiated; capsules immersed to short-exserted; calyptrae naked (species with contorted leaves) to hairy (species with unaltered leaves).
|[[Orthotrichum|Orthotrichum]]
|- id="key-5-73"
|73
|Leaves typically crispate to contorted when dry; basal marginal laminal cells with thickened transverse walls; capsules short-exserted; calyptrae hairy.
|[[Ulota|Ulota]]
|- id="key-5-69"
|69
|Costal stereid bands differentiated.
|[[#key-5-74| > 74]]
|- id="key-5-74"
|74
|Costal stereid bands single, dorsal.
|[[#key-5-75| > 75]]
|- id="key-5-75"
|75
|Calyptrae campanulate-mitrate, covering entire capsule, often lobed at base; basal laminal cells with thickened transverse walls.
|[[Encalypta|Encalypta]]
|- id="key-5-75"
|75
|Calyptrae cucullate, covering only operculum and capsule apex, unlobed at base; basal laminal cells usually without thickened transverse walls.
|[[#key-5-76| > 76]]
|- id="key-5-76"
|76
|Leaves broadly lanceolate (from revolute leaf margins), lingulate or oblong-ovate; apices sometimes with hair-points; margins recurved to strongly revolute; laminal cell papillae stellate from stipitate base to C -shaped.
|[[#key-5-77| > 77]]
|- id="key-5-77"
|77
|Leaves with intramarginal band of enlarged, smooth, often orange cells.
|[[Crumia|Crumia]]
|- id="key-5-77"
|77
|Leaves without differentiated intramarginal cells but sometimes with smooth, not enlarged marginal cells.
|[[#key-5-78| > 78]]
|- id="key-5-78"
|78
|Leaves narrowly lanceolate; margins erect, 2-stratose.
|[[Didymodon|Didymodon]]
|- id="key-5-78"
|78
|Leaves oblong, lingulate to ovate; margins plane to revolute, 1-stratose, or if 2-stratose then always revolute.
|[[#key-5-79| > 79]]
|- id="key-5-79"
|79
|Distal leaf margins broadly revolute to spirally revolute; marginal cells often more strongly chlorophyllose than medial cells.
|[[Pseudocrossidium|Pseudocrossidium]]
|- id="key-5-79"
|79
|Distal leaf margins plane to revolute; marginal cells undifferentiated or paler than medial cells.
|[[#key-5-80| > 80]]
|- id="key-5-80"
|80
|Leaves often bordered by smooth cells; peristome present.
|[[Tortula|Tortula]]
|- id="key-5-80"
|80
|Leaves unbordered; peristome absent or rudimentary.
|[[Microbryum|Microbryum]]
|- id="key-5-76"
|76
|Leaves linear-lanceolate to lanceolate; apices never with hair-points; margins recurved to plane; laminal cell papillae conic, clavate, or branched, rarely C -shaped.
|[[#key-5-81| > 81]]
|- id="key-5-81"
|81
|Laminal cell papillae 4 – 7, widely spaced, small, conic; elliptic propagula present in leaf axils; peristome double; usually on trees, rarely on rock.
|[[Zygodon|Zygodon]]
|- id="key-5-81"
|81
|Laminal cell papillae 1 – 3( – 4), closely set, simple to branched; propagula absent; peristome single or absent; on soil and rock.
|[[#key-5-82| > 82]]
|- id="key-5-82"
|82
|Leaf margins serrulate distally; capsules erect to inclined, often furrowed and strumose; peristome vertically pitted-striolate.
|[[Cynodontium|Cynodontium]]
|- id="key-5-82"
|82
|Leaf margins entire; capsules erect, never furrowed or strumose; peristome, when present, papillose.
|[[#key-5-83| > 83]]
|- id="key-5-83"
|83
|Basal laminal cells lax, hyaline; distal leaf margins 2-stratose throughout; peristome present.
|[[Didymodon|Didymodon]]
|- id="key-5-83"
|83
|Basal laminal cells firm-walled, pale but not hyaline; distal leaf margins 1-stratose or irregularly 2-stratose; peristome absent.
|[[#key-5-84| > 84]]
|- id="key-5-84"
|84
|Stems monopodial; archegonia on short, lateral branches; stems in transverse section rounded-triangular.
|[[Anoectangium|Anoectangium]]
|- id="key-5-84"
|84
|Stems sympodial; archegonia terminal on main stem; stems in transverse section round.
|[[Gymnostomum|Gymnostomum]]
|- id="key-5-74"
|74
|Costal stereid bands both dorsal and ventral.
|[[#key-5-85| > 85]]
|- id="key-5-85"
|85
|Leaf margins abruptly serrate at shoulders.
|[[Eucladium|Eucladium]]
|- id="key-5-85"
|85
|Leaf margins entire at shoulders.
|[[#key-5-86| > 86]]
|- id="key-5-86"
|86
|Laminal cell papillae many (more than 7), minute, elliptic, over walls and lumina.
|[[Amphidium|Amphidium]]
|- id="key-5-86"
|86
|Laminal cell papillae fewer than 7, larger, round, only over lumina.
|[[#key-5-87| > 87]]
|- id="key-5-87"
|87
|Leaf margins toothed distally.
|[[#key-5-88| > 88]]
|- id="key-5-88"
|88
|Laminae 2-stratose; margins 1-stratose.
|[[Rhexophyllum|Rhexophyllum]]
|- id="key-5-88"
|88
|Laminae 1-stratose; margins 1-or 2-stratose.
|[[#key-5-89| > 89]]
|- id="key-5-89"
|89
|Laminal cells bulging, mammillose to 1-papillose22-7. Dichodontium (in part), v. 27, p. 382
|[[#key-5-89| > 89]]
|- id="key-5-89"
|89
|Laminal cells not bulging, multipapillose.
|[[#key-5-90| > 90]]
|- id="key-5-90"
|90
|Stems with central strand present.
|[[Bryoerythrophyllum|Bryoerythrophyllum]]
|- id="key-5-90"
|90
|Stems with central strand absent.
|[[#key-5-91| > 91]]
|- id="key-5-91"
|91
|Stems with hyalodermis present; costal adaxial surface with enlarged, papillose cells.
|[[Trichostomum|Trichostomum]]
|- id="key-5-91"
|91
|Stems with hyalodermis absent; costal adaxial s urface with small, smooth cells.
|[[Leptodontium|Leptodontium]]
|- id="key-5-87"
|87
|Leaf margins entire or roughened with projecting papillae.
|[[#key-5-92| > 92]]
|- id="key-5-92"
|92
|Leaf margins at extreme apex with large, curved, projecting papillae.
|[[Dichodontium|Dichodontium]]
|- id="key-5-92"
|92
|Leaf margins at extreme apex entire or papillose-crenulate.
|[[#key-5-93| > 93]]
|- id="key-5-93"
|93
|Stems triquetrous, especially when moist; laminal cells 1-papillose, papillae sometimes branched; California.
|[[Triquetrella|Triquetrella]]
|- id="key-5-93"
|93
|Stems without ranked leaves; laminal cells multipapillose; widespread.
|[[#key-5-94| > 94]]
|- id="key-5-94"
|94
|Leaf margins recurved to revolute, at least near mid leaf or below.
|[[#key-5-95| > 95]]
|- id="key-5-95"
|95
|Peristome absent; leaves recurved only on one side.
|[[Hymenostylium|Hymenostylium]]
|- id="key-5-95"
|95
|Peristome usually present; leaves recurved on both sides.
|[[#key-5-96| > 96]]
|- id="key-5-96"
|96
|Axillary hairs with all cells hyaline; laminal cells obscure in surface view; leaves usually ovate to oblong; costal abaxial surface cells oblong to elongate; basal laminal cells usually strongly differentiated, hyaline, elongate.
|[[Barbula|Barbula]]
|- id="key-5-96"
|96
|Axillary hairs with brown basal cell; laminal cells well defined in surface view; leaves usually lanceolate; costal abaxial surface cells quadrate to short-oblong, rarely elongate; basal laminal cells usually little differentiated, green, short-rectangular.
|[[Didymodon|Didymodon]]
|- id="key-5-94"
|94
|Leaf margins plane to erect.
|[[#key-5-97| > 97]]
|- id="key-5-97"
|97
|Costae sinuous distally.
|[[Bellibarbula|Bellibarbula]]
|- id="key-5-97"
|97
|Costae straight distally.
|[[#key-5-98| > 98]]
|- id="key-5-98"
|98
|Stems with hyalodermis present.
|[[Trichostomum|Trichostomum]]
|- id="key-5-98"
|98
|Stems with hyalodermis absent, epidermal cells small.
|[[#key-5-99| > 99]]
|- id="key-5-99"
|99
|Leaf apices subtubulose; distal laminal cell papillae 1 or 2, large, centered, multifid.
|[[Tuerckheimia|Tuerckheimia]]
|- id="key-5-99"
|99
|Leaf apices flat; distal laminal cell papillae 3 – 6, small, scattered, simple, blunt.
|[[#key-5-100| > 100]]
|- id="key-5-100"
|100
|Perichaetia and sporophytes terminal; leaves less than 2 mm; axillary hairs of 8 – 10 cells.
|[[Gymnostomum|Gymnostomum]]
|- id="key-5-100"
|100
|Perichaetia and sporophytes lateral; leaves 2.2 – 3 mm; axillary hairs of 15 – 20 cells.
|[[Molendoa|Molendoa]]
|}
</div><!--
--><div class="treatment-key-group">
  <h3 class="treatment-key-header" id="key-6">Subkey F</h3>
{| class="wikitable fna-keytable"
|- id="key-6-1"
|1
|Laminal cells (3 – )4+:1, rectangular to long-hexagonal.
|[[#key-6-2| > 2]]
|- id="key-6-2"
|2
|Leaf apices acute to acuminate.
|[[#key-6-3| > 3]]
|- id="key-6-3"
|3
|Costae occupying 1/2 or more of leaf base; capsules curved, asymmetric, elongate-pyriform, neck as long as urn.
|[[Amblyodon|Amblyodon]]
|- id="key-6-3"
|3
|Costae occupying less than 1/4 leaf base; capsules straight, symmetric, shape variable but not elongate-pyriform, neck inconspicuous.
|[[#key-6-4| > 4]]
|- id="key-6-4"
|4
|Plants small, less than 2 mm, gregarious, on calcareous rock; capsules ovate.
|[[Seligeria|Seligeria]]
|- id="key-6-4"
|4
|Plants larger, mostly more than 5 mm, in tufts, on various substrates; capsules cylindric.
|[[#key-6-5| > 5]]
|- id="key-6-5"
|5
|Leaves flexuose-twisted when dry; capsules er ect; s Appalachians, California.
|[[Orthodontium|Orthodontium]]
|- id="key-6-5"
|5
|Leaves erect, little altered when dry; capsules erect or inclined; widespread.
|[[#key-6-6| > 6]]
|- id="key-6-6"
|6
|Capsules appearing lateral, erect; peristome single; leaves less than 1 mm; propagula absent.
|[[Mielichhoferia|Mielichhoferia]]
|- id="key-6-6"
|6
|Capsules terminal, inclined to pendent; peristome double; leaves usually more than 1 mm; axillary propagula sometimes present.
|[[Pohlia|Pohlia]]
|- id="key-6-2"
|2
|Leaf apices subulate.
|[[#key-6-7| > 7]]
|- id="key-6-7"
|7
|Capsules curved, asymmetric.
|[[Dicranella|Dicranella]]
|- id="key-6-7"
|7
|Capsules straight, symmetric (sometimes inclined to pendulous).
|[[#key-6-8| > 8]]
|- id="key-6-8"
|8
|Setae flexuose-curved to cygneous.
|[[#key-6-9| > 9]]
|- id="key-6-9"
|9
|Setae more than 1 cm; plants more than 5 mm; leaves more than 4 mm; capsules pyriform.
|[[Leptobryum|Leptobryum]]
|- id="key-6-9"
|9
|Setae less than 0.5 cm; plants less than 3 mm; leaves less than 2 mm; capsules hemispheric.
|[[#key-6-10| > 10]]
|- id="key-6-10"
|10
|Plants perennial, on rock, not in Florida; setae slender, twisted; peristome present.
|[[Seligeria|Seligeria]]
|- id="key-6-10"
|10
|Plants ephemeral, on soil in Florida; setae stout, curved at apex, not twisted; peristome absent.
|[[Eccremidium|Eccremidium]]
|- id="key-6-8"
|8
|Setae straight but sometimes spirally twisted.
|[[#key-6-11| > 11]]
|- id="key-6-11"
|11
|Peristome double; Arctic areas.
|[[Pseudoditrichum|Pseudoditrichum]]
|- id="key-6-11"
|11
|Peristome single; widespread.
|[[#key-6-12| > 12]]
|- id="key-6-12"
|12
|Capsules ovoid; on calcareous rock.
|[[Seligeria|Seligeria]]
|- id="key-6-12"
|12
|Capsules oblong to cylindric; generally on soil.
|[[#key-6-13| > 13]]
|- id="key-6-13"
|13
|Capsules short-cylindric; peristome teeth divided 1/2 their length, flat, vertically pitted-striolate.
|[[Dicranella|Dicranella]]
|- id="key-6-13"
|13
|Capsules long-cylindric; peristome teeth divided to base, terete, papillose.
|[[Ditrichum|Ditrichum]]
|- id="key-6-1"
|1
|Laminal cells 1( – 2):1, rounded to quadrate.
|[[#key-6-14| > 14]]
|- id="key-6-14"
|14
|Perichaetial leaves strongly differentiated, awns as long as lamina; leaves 2-stratose.
|[[Diphyscium|Diphyscium]]
|- id="key-6-14"
|14
|Perichaetial leaves slightly or not differentiated, never long-awned; leaves 1 – multistratose.
|[[#key-6-15| > 15]]
|- id="key-6-15"
|15
|Distal laminal cells in ascending oblique rows; cylindric brood bodies present on leaves; tomentum common.
|[[Zygodon|Zygodon]]
|- id="key-6-15"
|15
|Distal laminal cells not in oblique rows; brood bodies present or absent; tomentum absent or sparse.
|[[#key-6-16| > 16]]
|- id="key-6-16"
|16
|Capsules distinctly 8-or 16-ribbed and furrowed.
|[[#key-6-17| > 17]]
|- id="key-6-17"
|17
|Calyptrae mitrate.
|[[#key-6-18| > 18]]
|- id="key-6-18"
|18
|Calyptrae hairy.
|[[Ulota|Ulota]]
|- id="key-6-18"
|18
|Calyptrae naked.
|[[#key-6-19| > 19]]
|- id="key-6-19"
|19
|Annuli compound; calyptrae not plicate.
|[[Brachydontium|Brachydontium]]
|- id="key-6-19"
|19
|Annuli absent; calyptrae plicate.
|[[Orthotrichum|Orthotrichum]]
|- id="key-6-17"
|17
|Calyptrae cucullate.
|[[#key-6-20| > 20]]
|- id="key-6-20"
|20
|Setae cygneous; plants rare, in tight cushions on alpine slopes22-14. Oreas, v. 27, p. 425
|[[#key-6-20| > 20]]
|- id="key-6-20"
|20
|Setae erect (sometimes twisted); plants various but not as above.
|[[#key-6-21| > 21]]
|- id="key-6-21"
|21
|Capsules abruptly bent at seta-capsule junction and horizontal, often purple-red when mature.
|[[Ceratodon|Ceratodon]]
|- id="key-6-21"
|21
|Capsules erect to suberect, brown when mature.
|[[#key-6-22| > 22]]
|- id="key-6-22"
|22
|Peristome teeth divided to 1/2 their length; capsules cylindric to ovate-cylindric, 2 mm; Pacific Northwest.
|[[Cynodontium|Cynodontium]]
|- id="key-6-22"
|22
|Peristome teeth undivided; capsules ovoid, less than 1 mm; e, Midwestern United States, maritime Canada22-16. Rhabdoweisia, v. 27, p. 428
|[[#key-6-16| > 16]]
|- id="key-6-16"
|16
|Capsules smooth, or indistinctly furrowed when dry but without distinct ribs.
|[[#key-6-23| > 23]]
|- id="key-6-23"
|23
|Capsule neck elongate, well defined; peristome double.
|[[Meesia|Meesia]]
|- id="key-6-23"
|23
|Capsule neck short, inconspicuous; peristome single.
|[[#key-6-24| > 24]]
|- id="key-6-24"
|24
|Capsules inclined.
|[[#key-6-25| > 25]]
|- id="key-6-25"
|25
|Capsules 1.5 – 2 mm, pale, strumose; leaf margins 2-stratose; on moist soil, rock, and logs.
|[[Oncophorus|Oncophorus]]
|- id="key-6-25"
|25
|Capsules less than 1 mm, black, not strumose; leaf margins 1-stratose; in rich fens.
|[[Catoscopium|Catoscopium]]
|- id="key-6-24"
|24
|Capsules erect.
|[[#key-6-26| > 26]]
|- id="key-6-26"
|26
|Capsules immersed to short-exserted.
|[[Grimmia|Grimmia]]
|- id="key-6-26"
|26
|Capsules long-exserted.
|[[#key-6-27| > 27]]
|- id="key-6-27"
|27
|Calyptrae mitrate.
|[[#key-6-28| > 28]]
|- id="key-6-28"
|28
|Calyptrae not plicate; setae cygneous.
|[[Campylostelium|Campylostelium]]
|- id="key-6-28"
|28
|Calyptrae plicate; setae straight.
|[[Ptychomitrium|Ptychomitrium]]
|- id="key-6-27"
|27
|Calyptrae cucullate.
|[[#key-6-29| > 29]]
|- id="key-6-29"
|29
|Leaves oblong.
|[[Barbula|Barbula]]
|- id="key-6-29"
|29
|Leaves lanceolate from somewhat expanded base.
|[[Didymodon|Didymodon]]
|}
</div></div>