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Vascular Plants of California
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Polygonum aviculare subsp. buxiforme

Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key
Habit: Annual to shrub [tree]. Stem: nodes swollen or not. Leaf: simple, basal or cauline, generally alternate; ocreae present or 0, generally scarious, persistent or not. Inflorescence: flower clusters in axillary to terminal cyme-, panicle-, raceme-, spike-, umbel- or head-like arrangements, entire inflorescence or main inflorescence branches generally subtended by bracts ("inflorescence bracts"); peduncles present or 0; flower clusters in Eriogoneae-Eriogonoideae subtended by involucre of >= 1 free or +- fused, sometimes awn-tipped bracts ("involucre bracts") or, in Polygonoideae and rarely in Eriogonoideae, not (if bracts completely fused, involucre "tubular"); pedicels in Eriogoneae each often subtended by 2 free, transparent, linear bractlets or in Polygonoideae all subtended by 2+ fused, membranous, wide bractlets. Flower: generally bisexual, small, 1--200 per node; perianth parts 2--6, generally in 2 whorls, free or basally fused, generally petal-like, often +- concave adaxially, often darker at midvein, often turning +- red or +- brown in age; stamens [1]3 or 6--9 in 2 whorls; ovary superior, 1-chambered, ovule 1, styles 1--3. Fruit: achenes, included in or exserted from perianth, generally 3-angled, ovoid or elliptic, generally glabrous.
Genera In Family: 48 genera, +- 1200 species: worldwide, especially northern temperate; some cultivated for food (Coccoloba, sea-grape; Fagopyrum, Rheum, Rumex) or ornamental (Antigonon, lovechain; Coccoloba; Muehlenbeckia; Persicaria; Polygonum), a few timbered (Coccoloba; Triplaris). Several (Emex; Fallopia; Persicaria; Polygonum; Rumex) are weeds. Note: Treatment of genera in Eriogonoideae based on monographic work of James L. Reveal. Involucre number throughout is number (1--many) per ultimate grouping, at tips of ultimate branches; flower number is per flower cluster or involucre, unless otherwise stated. Fagopyrum esculentum Moench not naturalized, considered an historical waif (or garden weed +- presently), therefore not treated.
eFlora Treatment Author: Mihai Costea, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: PolygonumView DescriptionDichotomous Key

Common Name: KNOTWEED
Habit: Annual, perennial herb to shrub. Stem: prostrate to erect, 8--16-ribbed or 4--5-angled with ribs 0 or obscure; glabrous or papillate-scabrous. Leaf: cauline, alternate, petioled or not; ocrea generally jointed to leaf, generally cylindric proximally, generally translucent distally, white or silvery, 2-lobed, glabrous, disintegrating to fibers or completely; blade linear, lanceolate, elliptic, ovate, or subround, entire. Inflorescence: axillary, terminal, generally spike-like; peduncle 0; pedicels present or 0, included in to exserted from bractlets; flowers 1--7(10). Flower: bisexual, base not stalk-like; perianth not enlarging, bell- to urn-shaped, glabrous, white or green-white to pink; perianth parts 5, fused 3--60[70]%, petal- or sepal-like, similar [or not], outer +- keeled or not, < to > inner, midveins generally a different shade or color than rest of perianth; stamens 3--8 (some staminodes or not), filaments or at least innermost free, wider at base, fused to perianth tube or not, anthers elliptic to oblong, white-yellow or generally pink to purple (orange-pink); styles (2)3, generally spreading, free or fused basally, stigmas 2--3, head-like. Fruit: included or exserted, wings 0, angles (2)3, 1 face much narrower than other (1)2 or not; tip beak-like, yellow-green, brown, or black. Seed: embryo curved.
Species In Genus: +- 65 species: +- worldwide; sect. Duravia restricted to western North America. Etymology: (Greek: poly, many, gony, knee joint, or gone, seed, of uncertain meaning) Note: Many species of sect. Polygonum with 2 kinds of fruit, differing in germination and morphology (summer fruit brown, ovate, tubercled to smooth; late-season fruit olive-green, lanceolate, smooth, 2--5 × > summer), but of little taxonomic importance. Mature, early-season plants with leaves, flowers, fruits needed for identification. Flowers "closed" or "1/2-open" should be determined on herbarium specimens. Other taxa in TJM (1993) moved to Aconogonon, Bistorta, Fallopia, Persicaria.
eFlora Treatment Author: Mihai Costea
Reference: Costea 2005 Brittonia 57:1--27
Species: Polygonum aviculareView Description 

Habit: Annual. Stem: prostrate to erect, 5--200 cm, glabrous, green, ribbed, branched. Leaf: distal > distal flowers; ocreae 3--15 mm, distally disintegrating to fibers or +- completely persistent; petiole 0.3--9 mm; blade 6--50(60) mm, 0.5--22 mm wide, narrowly elliptic, lanceolate, elliptic, or obovate, green to gray-green, margin flat, tip acute or rounded. Inflorescence: axillary; flowers 1--6(8), crowded distally or not; pedicels included to exserted, 1.5--5 mm. Flower: closed or half-open; perianth 1.8--5.5 mm, generally not pouched at base, +- green, margin white to red, tube 20--57% of length, lobes overlapped or not, not keeled, oblong to obovate, tip rounded, generally hood-shaped, midvein branched or not; stamens 5--8. Fruit: included or exserted, 1.2--4.2 mm, ovate, light- to dark-brown, dull, (2)3--angled, faces +- unequal, generally coarsely striate-tubercled; late-season common or not, 2--5 mm. Chromosomes: 2n=40,60.
Note: Taxonomically controversial, generally self-pollinated, self-fertilized, polyploid complex in which varieties to species have been named, but intergradation precludes recognition as species.
Polygonum aviculare subsp. buxiforme (Small) Costea & Tardif
Habit: Annual. Stem: 1--many, generally mat-forming, prostrate to ascending, (5)20--70(200) cm, branches many. Leaf: stem leaves 1--2.5 × > branch leaves; ocreae 3.5--6.5 mm, each proximally cylindric, distally +- persistent, especially on upper leaves, silvery, eventually disintegrating +- completely; petiole 0.3--2 (3.5) mm, blade lanceolate to elliptic, oblanceolate, or obovate, 6--30(45) mm, 3--6(13) mm wide, 2.5--5.6(10) × as long as wide, tip acute to obtuse. Inflorescence: flowers 3--6, generally crowded distally; pedicels generally included, 1--2.5 mm. Flower: perianth (2)2.3--3.4(3.6) mm, +- pouched at base, green, margins white (pink), tube 20--36% of length, lobes overlapped, oblong, hood-shaped, veins branched, thickened to strongly so. Fruit: generally included, (1.8)2--2.8(3) mm, ovate, light-brown to brown, 3-angled, faces subequal, tip straight, coarse-striate to obscure-tubercled; late-season common, 2.5--5 mm. Chromosomes: 2n=60.
Ecology: Disturbed places, nondrifting sands, borders of marshes, dunes; Elevation: < 3000 m. Bioregional Distribution: CA; Distribution Outside California: North America. Flowering Time: Jul--Nov Note: May be naturalized in California.
Synonyms: Polygonum buxiforme Small
Jepson eFlora Author: Mihai Costea
Reference: Costea 2005 Brittonia 57:1--27
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Citation for this treatment: Mihai Costea 2012, Polygonum aviculare subsp. buxiforme, in Jepson Flora Project (eds.) Jepson eFlora, /eflora/eflora_display.php?tid=80989, accessed on May 31, 2020.

Citation for the whole project: Jepson Flora Project (eds.) 2020, Jepson eFlora,, accessed on May 31, 2020.

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Geographic subdivisions for Polygonum aviculare subsp. buxiforme:
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map of distribution 1
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Data provided by the participants of the  Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).