Persicaria arifolia |
Polygonaceae subfam. polygonoideae |
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halberd-leaf smartweed, halberd-leaf tearthumb, renouée à feuilles d'arum |
knotweed |
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Habit | Plants annual, 2–15 dm; roots also often arising from proximal nodes. | Trees, shrubs, vines, or herbs, perennial or annual, homophyllous (heretophyllous in some species of Polygonum); root fibrous or a solid taproot, rarely tuberous. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | scandent, ribbed, glabrous; prickles 0.5–1 mm. |
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 tan or brownish, cylindric, 8–15 mm, chartaceous, base inflated or not, with prickles, margins oblique, ciliate with bristles 0.5–2.5 mm, surface glabrous or appressed- to spreading-pubescent; petiole 1–7 cm; blade broadly hastate to hastate-cordate or triangular, (2–)6.5–13(–18) × (1–)6–11(–16) cm, base truncate to truncate-cordate, margins broadly hastate with lobes divergent, ciliate, sometimes also retrorsely prickly, apex acuminate, faces appressed-pubescent or, rarely, glabrous adaxially, stellate-pubescent or, rarely, glabrous abaxially, major veins often bearing prickles. |
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 | capitate or paniclelike, uninterrupted, 5–12 × 3–8 mm; peduncle 10–80 mm, retrorsely prickly proximally, stellate-pubescent and stipitate-glandular distally, glands red or pink; ocreolae usually overlapping, sometimes not overlapping proximally, margins eciliate or ciliate with bristles to 0.5 mm. |
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 | mostly ascending, 2–3 mm. |
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Flowers | 2–4 per ocreate fascicle; perianth pink or red, often whitish green proximally, glabrous, accrescent, not becoming blue and fleshy in fruit; tepals 4, connate 1/3–1/2 their length, broadly elliptic, 5–6 mm, apex acute to obtuse; stamens (6–)8, filaments distinct, free; anthers pink, elliptic; styles 2, distinct. |
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 | included, dark brown to black, biconvex, 3.5–6 × 3–4 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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Persicaria arifolia |
Polygonaceae subfam. polygonoideae |
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Phenology | Flowering Jul–Oct. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Shaded swamps, ponds, tidal marshes along rivers, wet ravines in forests | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 0-600 m (0-2000 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
CT; DC; DE; GA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WA; WI; WV; NB; NS; ON; PE; QC
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Mainly temperate regions of North America |
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Discussion | 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. 577. | FNA vol. 5, p. 479. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Echinocaulon | Polygonaceae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | Polygonum arifolium, Polygonum arifolium var. lentiforme, Polygonum arifolium var. pubescens, Polygonum sagittatum var. pubescens, Tracaulon arifolium, Truellum arifolium | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Linnaeus) Haraldson: Acta Univ. Upsal., Symb. Bot. Upsal. 22: 72. (1978) | Eaton: Bot. Dict. ed. 4, 30. (1836) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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