View source for Isocoma

{{Treatment/ID
|accepted_name=Isocoma
|accepted_authority=Nuttall
|publications={{Treatment/Publication
|title=Trans. Amer. Philos. Soc., n. s.
|place=7: 320. 1840
|year=1840
}}
|common_names=Jimmyweed;goldenweed
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Haplopappus sect. Isocoma
|authority=(Nuttall) H. M. Hall
}}
|hierarchy=Asteraceae;Asteraceae tribe Astereae;Isocoma
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Astereae]]</div><div class="higher-taxon"><small>genus</small>[[Isocoma]]</div></div>
|etymology=Greek isos, equal, and kome, hair of the head; “so called from its equal flowers” (protologue)
|volume=Volume 20
|mention_page=page 7, 13, 89, 438, 445
|treatment_page=page 439
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Perennials </b>or subshrubs, (4–)20–120(–150) cm (bases often woody). <b>Stems</b> usually strictly erect, few-branched, glabrous or hispidulous, villous, or tomentose, usually gland-dotted (sessile or slightly sunken in pits), sometimes stipitate-glandular, rarely eglandular, often resinous. <b>Leaves</b> mostly cauline; alternate; sessile; blades 1-nerved, linear to oblanceolate or obovate, margins entire or toothed to pinnatifid (teeth or lobes often spinulose-tipped), faces glabrous or hispidulous, villous, or tomentose, usually gland-dotted (in pits). <b>Heads</b> discoid, (sessile or subsessile) in compact clusters borne in terminal corymbiform arrays, rarely borne singly. <b>Involucres</b> obconic to turbinate or campanulate, (3–9.5 ×) 2–8 mm. <b>Phyllaries</b> 15–30 in (3–)4–6 series, 1-nerved (midnerves usually barely evident; flat to convex), oblong- to elliptic-lanceolate, unequal, margins narrowly scarious, apices sometimes green, faces glabrous or tomentose, sometimes gland-dotted, sometimes with resin pockets. <b>Receptacles</b> flat, pitted, epaleate. <b>Disc</b> florets 8–34, bisexual, fertile; corollas yellow with dark orange-resinous veins, tubes (with at least a few glandular hairs) longer than abruptly ampliate, goblet-shaped throats (tube elevating corollas above involucres at flowering), lobes 5, erect, deltate (elongating at maturity, unequal, outer prominently bent or leaning outward, abruptly enlarged); style-branch appendages narrowly triangular. <b>Cypselae</b> (brownish) obpyramidal, terete or subterete, 5–11-ribbed (sometimes thick and resinous), faces sericeous; pappi persistent, of 40–50 unevenly thick, unequal, barbellate, apically attenuate bristles in 2(–3) series. <b>x</b> = 6.</span><!--

-->{{Treatment/Body
|distribution=sw United States;Mexico.
|discussion=<p>Species 16 (10 in the flora).</p><!--
--><p><i>Isocoma</i> is recognized by its subshrubby habit, gland-dotted (sometimes stipitate-glandular), often resinous leaves, compactly clustered discoid heads in terminal, corymbiform arrays, goblet-shaped disc corollas, and base chromosome number of x = 6. H. M. Hall (1928) regarded the group as a section of Haplopappus, as did A. Cronquist (1994). Naturally occurring hybrids in south-central Mexico have been observed between <i>Isocoma</i> veneta (Kunth) Greene and <i>Xanthocephalum</i> humile (Kunth) Bentham (R. L. Hartman and M. A. Lane 1991).</p>
|tables=
|references={{Treatment/Reference
|id=nesom1991b
|text=Nesom, G. L. 1991c. Taxonomy of Isocoma (Asteraceae: Astereae). Phytologia 70: 69–114.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Phyllary apices with strongly developed resin pockets
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Phyllary apices gland-dotted (rarely so in I. coronopifolia), lacking resin pockets or pockets small, weakly developed
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Teeth or lobes of leaf margins apically rounded-obtuse; florets 8–27; phyllary apices not spinulose-aristate, or if spinulose-aristate, then florets 20–27
|[[Isocoma acradenia|Isocoma acradenia]]
|-id=key-0-2
|2
|Teeth or lobes of leaf margins apically spinulose; florets 10–13; phyllary apices spinulose-aristate
|[[Isocoma arguta|Isocoma arguta]]
|-id=key-0-3
|3
|Leaves pinnatifid
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Leaves entire or shallowly toothed to lobed, not pinnatifid
|[[#key-0-6| > 6]]
|-id=key-0-4
|4
|Herbage minutely hispidulous or sparsely puberulous (at least distal stems)
|[[Isocoma tenuisecta|Isocoma tenuisecta]]
|-id=key-0-4
|4
|Herbage glabrous
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Involucres 5–7.5 mm wide; florets 18–25
|[[Isocoma azteca|Isocoma azteca]]
|-id=key-0-5
|5
|Involucres 2.5–4 mm wide; florets 12–15
|[[Isocoma coronopifolia|Isocoma coronopifolia]]
|-id=key-0-6
|6
|Phyllary apices distinctly aristate-spinulose; florets 10–13; California
|[[Isocoma arguta|Isocoma arguta]]
|-id=key-0-6
|6
|Phyllary apices not aristate-spinulose; florets 8–34; California and eastward
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Involucres 3.2–7 × 2.5–4 mm; florets 8–17(–21)
|[[#key-0-8| > 8]]
|-id=key-0-7
|7
|Involucres 5–9 × 4.5–8 mm; florets (15–)18–34
|[[#key-0-9| > 9]]
|-id=key-0-8
|8
|Leaves never stipitate-glandular but almost always resinous, glabrous; involucres 5–7 mm
|[[Isocoma coronopifolia|Isocoma coronopifolia]]
|-id=key-0-8
|8
|Leaves sometimes stipitate-glandular, never resinous, margins hispidulous, sometimes also on faces; involucres 3.2–5.5 mm
|[[Isocoma pluriflora|Isocoma pluriflora]]
|-id=key-0-9
|9
|Leaves 5–10(–18) mm; corollas 4–5 mm
|[[Isocoma humilis|Isocoma humilis]]
|-id=key-0-9
|9
|Leaves (in I. menziesii 5–)13–50 mm; corollas 5–7.5 mm
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Leaf margins entire or toothed to lobed; California
|[[Isocoma menziesii|Isocoma menziesii]]
|-id=key-0-10
|10
|Leaf margins entire; e of California
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Involucres (5.5–)6–9.5 × 5–7.5 mm; phyllary apices yellowish to greenish yellow, sparsely or not at all gland-dotted; florets 19–25, corollas 5–6.5 mm; cypsela ribs forming hornlike extensions; Arizona, Colorado, New Mexico, Utah
|[[Isocoma rusbyi|Isocoma rusbyi]]
|-id=key-0-11
|11
|Involucres (5.5–)6.5–8 × 4.5–5.5(–7) mm; phyllary apices usually green, usually densely gland-dotted; florets (18–)22–34, corollas 5.8–7.5 mm; cypsela ribs not forming hornlike extensions; Texas
|[[Isocoma drummondii|Isocoma drummondii]]
|}
</div></div><!--

-->{{#Taxon:
name=Isocoma
|author=Guy L. Nesom
|authority=Nuttall
|rank=genus
|parent rank=tribe
|synonyms=Haplopappus sect. Isocoma
|basionyms=
|family=Asteraceae
|illustrator=Barbara Alongi
|distribution=sw United States;Mexico.
|reference=nesom1991b
|publication title=Trans. Amer. Philos. Soc., n. s.
|publication year=1840
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/8f726806613d60c220dc4493de13607dd3150896/coarse_grained_fna_xml/V19-20-21/V20_1005.xml
|tribe=Asteraceae tribe Astereae
|genus=Isocoma
}}<!--

-->[[Category:Treatment]][[Category:Asteraceae tribe Astereae]]