View source for Pterostegia

{{Treatment/ID
|accepted_name=Pterostegia
|accepted_authority=Fischer & C. A. Meyer
|publications={{Treatment/Publication
|title=Bot. Dict. ed.
|place=4, 30. 1836
|year=1836
}}
|common_names=Knotweed
|basionyms=
|synonyms=
|hierarchy=Polygonaceae;Polygonaceae subfam. Polygonoideae;Pterostegia
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Polygonaceae]]</div><div class="higher-taxon"><small>subfamily</small>[[Polygonaceae subfam. Polygonoideae]]</div><div class="higher-taxon"><small>genus</small>[[Pterostegia]]</div></div>
|volume=Volume 5
|mention_page=page 216, 217, 218
|treatment_page=page 479
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Trees,</b> shrubs, vines, or herbs, perennial or annual, homophyllous (heretophyllous in some species of <i>Polygonum</i>); root fibrous or a solid taproot, rarely tuberous. <b>Stems</b> usually prostrate to erect, sometimes scandent, not scapose, rarely with recurved spines (some species of <i>Persicaria</i>), glabrous or pubescent, sometimes glandular; nodes usually swollen; branches free (adnate to stems distal to nodes and appearing to arise internodally in <i>Polygonella</i>); tendrils absent (except in <i>Antigonon</i> and <i>Brunnichia</i>). <b>Leaves</b> deciduous (persistent in <i>Coccoloba</i> and sometimes more than 1 year in <i>Antigonon</i> and <i>Polygonella</i>), basal or basal and cauline, rarely cauline only, mostly alternate; ocrea present, persistent or deciduous, cylindric to funnelform, chartaceous, membranous, coriaceous, or, rarely, foliaceous or partly so; petiole present or absent, rarely articulate basally (<i>Fagopyrum</i>, <i>Fallopia</i>, <i>Polygonella</i>, <i>Polygonum</i>), rarely with extrafloral nectaries (<i>Fallopia</i>, <i>Muehlenbeckia</i>); blade simple with entire margins, rarely undulate or lobed. <b>Inflorescences</b> terminal or terminal and axillary, spikelike, racemelike, paniclelike, cymelike, or, rarely, capitate, comprising simple or branched clusters of compound inflorescences; bracts absent; peduncle spreading to erect, sometimes absent; clusters of flowers subtended by connate bracteoles forming persistent membranous tube (ocreola), awnless. <b>Flowers</b> usually bisexual, sometimes bisexual and unisexual on same plant, rarely unisexual only, 1–20+ per ocreate fascicle, often with stipelike base distal to articulation; perianth often accrescent in fruit, often greenish, white, pink, yellow, red, or purple, usually unwinged and unkeeled (winged or, sometimes, keeled in <i>Fallopia</i>, rarely keeled in <i>Polygonum</i>), campanulate or urceolate, sometimes membranous, indurate, or fleshy in fruit, rarely developing raised tubercles proximally (<i>Rumex</i>), glabrous or pubescent, sometimes glandular or glandular-punctate; tepals 2–6, usually in 2 whorls, distinct or connate proximally and forming tube, petaloid or sepaloid, monomorphic or dimorphic; nectary a disk at base of ovary or glands associated with bases of filaments; stamens usually (1–)6–9, staminodes rarely present; filaments distinct, or connate basally and sometimes forming staminal tube, free or adnate to perianth tube; pistils (2–)3(–4)-carpellate; ovary 1-locular (sometimes with vestigial partitions proximally); ovule 1, orthotropous or, rarely, anatropous, placentation basal or free-central; styles 1–3, erect to spreading or recurved, distinct or connate proximally; stigmas peltate, capitate, fimbriate, or penicillate. <b>Achenes</b> yellowish, brown, red, or black, homocarpic (sometimes heterocarpic in <i>Polygonum</i>), winged or unwinged, usually 2–3-gonous, sometimes discoid, biconvex, or spheroidal, rarely 4-gonous. <b>Seeds</b>: embryo usually straight or curved, rarely folded.</span><!--

-->{{Treatment/Body
|distribution=Mainly temperate regions of North America.
|discussion=<p>Genera 28, species ca. 850 (16 genera, 160 species in the flora).</p><!--
--><p>Morphological (K. Haraldson 1978; L.-P. Ronse Decraene and J. R. Akeroyd 1988; Ronse Decraene et al. 2000; Hong S. P. et al. 1998) and molecular (A. S. Lamb Frye and K. A. Kron 2003) data provide support for separation of <i>Persicaria</i> from <i>Polygonum</i>. Further studies are needed to elucidate the relationships of allied genera, particularly <i>Aconogonon</i>, <i>Bistorta</i>, and <i>Koenigia</i> with <i>Persicaria</i>, and <i>Fallopia</i> and <i>Polygonella</i> with <i>Polygonum</i>.</p>
|tables=
|references={{Treatment/Reference
|id=haraldson1978a
|text=Haraldson, K. 1978. Anatomy and taxonomy in Polygonaceae subfam. Polygonoideae Meisn. emend. Jaretzky. Acta Univ. Upsal., Symb. Bot. Upsal. 22: 1–93.
}}{{Treatment/Reference
|id=hong1998a
|text=Hong, S. P., L.-P. Ronse Decraene, and E. Smets. 1998. Systematic significance of tepal surface morphology in tribes Persicarieae and Polygoneae (Polygonaceae). Bot. J. Linn. Soc. 127: 91–116.
}}{{Treatment/Reference
|id=ronse1988a
|text=Ronse Decraene, L.-P. and J. R. Akeroyd. 1988. Generic limits in Polygonum and related genera (Polygonaceae) on the basis of floral characters. Bot. J. Linn. Soc. 98: 321–371.
}}{{Treatment/Reference
|id=ronse2000a
|text=Ronse Decraene, L.-P., Hong S. P., and E. Smets. 2000. Systematic significance of fruit morphology and anatomy in tribes Persicarieae and Polygoneae (Polygonaceae). Bot. J. Linn. Soc. 134: 301–377.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Tendrils present; plants vines
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Tendrils absent; plants trees, shrubs, or herbs, rarely vinelike shrubs
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Perianths pink to purple or, rarely, white or yellow, membranous; pedicels not 3-winged
|[[Antigonon|Antigonon]]
|-id=key-0-2
|2
|Perianths green to greenish yellow, indurate; pedicels 3-winged, 1 wing more prominent and becoming greatly expanded in fruit
|[[Brunnichia|Brunnichia]]
|-id=key-0-3
|3
|Plants trees or shrubs; tubes of pistillate flowers becoming fleshy in fruit
|[[Coccoloba|Coccoloba]]
|-id=key-0-3
|3
|Plants herbs, subshrubs, or, rarely, vinelike shrubs; tubes of pistillate flowers rarely becoming fleshy in fruit
|[[#key-0-4| > 4]]
|-id=key-0-4
|4
|Tepals 6
|[[#key-0-5| > 5]]
|-id=key-0-4
|4
|Tepals 3, 4, or 5
|[[#key-0-7| > 7]]
|-id=key-0-5
|5
|Flowers unisexual; outer 3 tepals of pistillate flowers each with apex ending in stout spine
|[[Emex|Emex]]
|-id=key-0-5
|5
|Flowers bisexual or, rarely, unisexual; outer 3 tepals each without apex ending in stout spine
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Achenes winged; inner tepals of fruiting perianths nonaccrescent; stamens (6-)9
|[[Rheum|Rheum]]
|-id=key-0-6
|6
|Achenes unwinged; inner tepals of fruiting perianths usually accrescent; stamens 6
|[[Rumex|Rumex]]
|-id=key-0-7
|7
|Herbs annual; tepals 3 [4]; stamens (1-)3[-5]
|[[Koenigia|Koenigia]]
|-id=key-0-7
|7
|Herbs perennial or annual, or shrubs; tepals 4-5; stamens 3-8
|[[#key-0-8| > 8]]
|-id=key-0-8
|8
|Tepals 4; achenes lenticular, winged; leaves mostly basal
|[[Oxyria|Oxyria]]
|-id=key-0-8
|8
|Tepals 4 or 5; achenes 3-gonous, discoid, biconvex, spheroidal, or 4-gonous, unwinged or essentially so; leaves cauline or basal and cauline, rarely mostly basal
|[[#key-0-9| > 9]]
|-id=key-0-9
|9
|Branches adnate to stems, appearing to arise internodally
|[[Polygonella|Polygonella]]
|-id=key-0-9
|9
|Branches not adnate to stems, not appearing to arise internodally
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Plants shrubs, vinelike; flowers unisexual, tubes of pistillate flowers becoming fleshy in fruit
|[[Muehlenbeckia|Muehlenbeckia]]
|-id=key-0-10
|10
|Plants herbs or, if shrubs, not vinelike; flowers bisexual or, rarely, unisexual, if unisexual then tubes of pistillate flowers not becoming fleshy
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Outer tepals winged or keeled
|[[#key-0-12| > 12]]
|-id=key-0-11
|11
|Outer tepals unwinged and unkeeled
|[[#key-0-13| > 13]]
|-id=key-0-12
|12
|Outer tepals winged (keeled in F. ciliondis and, usually, F. convolvulus); ocreae chartaceous, tan to brownish, glabrous or scabrous to variously pubescent, never 2-lobed distally
|[[Fallopia|Fallopia]]
|-id=key-0-12
|12
|Outer tepals keeled; ocreae often hyaline, silvery, glabrous, 2-lobed distally
|[[Polygonum|Polygonum]]
|-id=key-0-13
|13
|Leaves mostly basal, some cauline; inflorescences terminal, spikelike; stems simple
|[[Bistorta|Bistorta]]
|-id=key-0-13
|13
|Leaves cauline; inflorescences terminal and axillary or axillary; stems usually branched, rarely simple
|[[#key-0-14| > 14]]
|-id=key-0-14
|14
|Achenes strongly exserted; perianths nonaccrescent; tepals distinct
|[[Fagopyrum|Fagopyrum]]
|-id=key-0-14
|14
|Achenes included or exserted; perianths accrescent or nonaccrescent; tepals connate to 2/3 their lengths. [15. Shifted to left margin.—Ed.]
|[[#key-0-15| > 15]]
|-id=key-0-15
|15
|Ocreae often hyaline, silvery, glabrous, 2-lobed distally, often disintegrating into fibers or completely
|[[Polygonum|Polygonum]]
|-id=key-0-15
|15
|Ocreae chartaceous, usually tan, brown, or reddish, rarely silvery, glabrous or scabrous to variously pubescent, never 2-lobed distally, often tearing with age
|[[#key-0-16| > 16]]
|-id=key-0-16
|16
|Inflorescences spikelike, paniclelike, or capitate; tepals 4 or 15, connate 1/ 2/ 3 their length (less than 5 their length in P. wallichii); stamens 5-8
|[[Persicaria|Persicaria]]
|-id=key-0-16
|16
|Inflorescences racemelike or paniclelike; tepals 5, connate ca. 1/ 4 their length; stamens 8
|[[Aconogonon|Aconogonon]]
|}
</div></div><!--

-->{{#Taxon:
name=Pterostegia
|author=Craig C. Freeman
|authority=Fischer & C. A. Meyer
|rank=genus
|parent rank=subfamily
|synonyms=
|basionyms=
|family=Polygonaceae
|distribution=Mainly temperate regions of North America.
|reference=haraldson1978a;hong1998a;ronse1988a;ronse2000a
|publication title=Bot. Dict. ed.
|publication year=1836
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-data-curation.git/src/bb6b7e3a7de7d3b7888a1ad48c7fd8f5c722d8d6/coarse_grained_fna_xml/V5/V5_1003.xml
|subfamily=Polygonaceae subfam. Polygonoideae
|genus=Pterostegia
}}<!--

-->[[Category:Treatment]][[Category:Polygonaceae subfam. Polygonoideae]]