Bistorta bistortoides |
Polygonaceae subfam. polygonoideae |
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American bistort, smokeweed, western bistort |
knotweed |
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Habit | Plants (10–)20–70(–75) cm; rhizomes contorted. | Trees, shrubs, vines, or herbs, perennial or annual, homophyllous (heretophyllous in some species of Polygonum); root fibrous or a solid taproot, rarely tuberous. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | 1–3. |
usually prostrate to erect, sometimes scandent, not scapose, rarely with recurved spines (some species of Persicaria), glabrous or pubescent, sometimes glandular; nodes usually swollen; branches free (adnate to stems distal to nodes and appearing to arise internodally in Polygonella); tendrils absent (except in Antigonon and Brunnichia). |
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Leaves | ocrea brown, cylindric, 9–25(–32) mm, margins oblique, glabrous; petiole attached to sheath 10–35(–50) mm, usually wingless, rarely winged distally, (10–)30–70(–110) mm; blade elliptic to oblong-lanceolate or oblong-oblanceolate, (3.5–)5–22 × 0.8–4.8 cm, base tapered to rounded, rarely abruptly truncate or cuneate, often asymmetric, margins entire, sometimes wavy, apex usually acute to acuminate, rarely obtuse, abaxial face glabrous or pubescent with whitish or brownish hairs, glaucous, adaxial face glabrous, not glaucous; cauline leaves 2–6, petiolate proximally, sessile distally, gradually reduced distally, blade elliptic or lanceolate to linear-lanceolate. |
deciduous (persistent in Coccoloba and sometimes more than 1 year in Antigonon and Polygonella), 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 (Fagopyrum, Fallopia, Polygonella, Polygonum), rarely with extrafloral nectaries (Fallopia, Muehlenbeckia); blade simple with entire margins, rarely undulate or lobed. |
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Inflorescences | 1(–2), short-cylindric to ovoid, (10–)20–40(–50) × (8–)12–25 mm, bulblets absent; peduncle 1–10 cm. |
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. |
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Pedicels | ascending or spreading, 2–8(–11) mm. |
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Flowers | 1–2 per ocreate fascicle; perianth white or pale pink; tepals oblong, 4–5 mm, apex obtuse to acute; stamens exserted; anthers yellow, elliptic. |
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 Fallopia, rarely keeled in Polygonum), campanulate or urceolate, sometimes membranous, indurate, or fleshy in fruit, rarely developing raised tubercles proximally (Rumex), 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. |
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Achenes | yellowish brown or olive-brown, 3.2–4.2 × 1.3–2 mm, shiny, smooth. |
yellowish, brown, red, or black, homocarpic (sometimes heterocarpic in Polygonum), winged or unwinged, usually 2–3-gonous, sometimes discoid, biconvex, or spheroidal, rarely 4-gonous. |
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Seeds | embryo usually straight or curved, rarely folded. |
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2n | = 24. |
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Bistorta bistortoides |
Polygonaceae subfam. polygonoideae |
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Phenology | Flowering Jul–Sep. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Streambanks, moist or swampy meadows, alpine slopes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 1300-3800 m (4300-12500 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB; BC
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Mainly temperate regions of North America |
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Discussion | Infrequent specimens of Bistorta bistortoides have basal leaf blades that are lance-ovate and abruptly contracted at the bases, and petioles distinctly winged distally, similar to those of B. officinalis. Roots of western bistort were used in soups and stews by the Blackfoot, boiled with meat by the Cherokee, and used in a poultice that was applied to sores and boils by the Miwok (D. E. Moerman 1998). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 28, species ca. 850 (16 genera, 160 species in the flora). 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 Persicaria from Polygonum. Further studies are needed to elucidate the relationships of allied genera, particularly Aconogonon, Bistorta, and Koenigia with Persicaria, and Fallopia and Polygonella with Polygonum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5, p. 596. | FNA vol. 5, p. 479. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Bistorta | Polygonaceae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | Polygonum bistortoides, B. bistortoides var. oblongifolia, Persicaria bistortoides, Polygonum bistortoides var. linearifolium, Polygonum bistortoides var. oblongifolium | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Pursh) Small: Bull. Torrey Bot. Club 33: 57. (1906) | Eaton: Bot. Dict. ed. 4, 30. (1836) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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