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Mihai Costea, except as noted

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.
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. [Freeman & Reveal 2005 FNANM 5:216–601] 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. Scientific Editors: Thomas J. Rosatti, Bruce G. Baldwin.

Key to Polygonaceae


1 sp. (Latin: twice twisted, from contorted rhizomes)
Unabridged etymology: (Latin: bi-, twice, tortus, twisted, alluding to contorted rhizomes)

B. bistortoides (Pursh) Small WESTERN BISTORT
Perennial herb, rhizomes contorted. Stem: (10)20–70 cm, branches 0. Leaf: generally basal; ocrea cylindric, 10–25(30) mm, brown, margins oblique, glabrous; petiole 10–30(50) mm; blade 4–30 cm, 1–4.8 cm wide, elliptic to lance-oblong or oblanceolate, base tapered to rounded, generally oblique, abaxially hairs 0 or ± white or ± brown, glaucous, adaxially hairs 0, margins entire, tip generally acute to acuminate; cauline leaves 2–4, petioled proximally, sessile distally, gradually reduced upward; blade elliptic or lanceolate to lance-linear. Inflorescence: terminal, spike-like, (10)20–40(50) mm, 10–25 mm wide, short-cylindric to ovoid; peduncle 1–10 cm; pedicel ascending or spreading, 2–10 mm; flowers 1–2. Flower: bisexual; perianth 4–5 mm, not enlarging, bell-shaped, glabrous, white or pale pink, parts 5, fused ± 1/5, oblong, tips obtuse to acute; stamens 5–8, exserted, anthers yellow, elliptic. Fruit: 3–4 mm, 1.2–2 mm wide, obovoid, light- or olive-brown, shiny, smooth.
2n=24. Wet meadows, streambanks, alpine slopes; 1500–3000 m. California Floristic Province (uncommon in coastal freshwater marshes, 0–20 m, North Coast, n Central Coast), n East of Sierra Nevada; to Alaska, eastern North America. [Polygonum bistortoides Pursh] Jul–Sep [Online Interchange]

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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora,, accessed on Nov 29 2015
Citation for this treatment: [Author of taxon treatment] 2013. Bistorta, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on Nov 29 2015

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click for enlargement Bistorta bistortoides
See CalPhotos for additional images
© 2007 Dr. Mark S. Brunell

Geographic subdivisions indicated for the distribution of Bistorta bistortoides Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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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.
Blue line denotes eFlora flowering time.