Polygonella americana |
Polygonella polygama |
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American jointweed, southern jointweed |
october-flower |
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Habit | Subshrubs, perennial, synoecious, 5.5–9 dm. | Subshrubs, perennial, dioecious, 1.5–7 dm. | ||||||||
Stems | erect, branched proximally and basally, glabrous. |
erect or decumbent, usually branched proximally and distally, glabrous or minutely pubescent. |
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Leaves | persistent; ocrea margins not ciliate; blade linear to spatulate, (4–)5–12(–19) × 0.5–0.9(–1.2) mm, base barely tapered, margins not hyaline, apex obtuse to acute, often erose, glabrous. |
persistent; ocrea margins not ciliate; blade linear to narrowly clavate or broadly spatulate, (3–)4–16(–36) × (0.3–)0.6–3.6(–5) mm, base barely tapered to attenuate, margins hyaline at least along distal 1/2, apex obtuse, glabrous. |
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Inflorescences | (7–)18–30(–60) mm; ocreola encircling rachis, only the base adnate to rachis, apex acuminate. |
(2–)4–20(–33) mm; ocreola encircling rachis, only the base adnate to rachis, apex acute to acuminate. |
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Pedicels | spreading in anthesis and fruit, 0.4–2.3 mm, usually much longer than subtending ocreola. |
spreading in anthesis, spreading to reflexed in fruit, 0.2–0.9 mm, as long or much longer than subtending ocreola. |
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Flowers | bisexual; outer tepals sharply reflexed early in anthesis and in fruit, white to pink, elliptic to ovate, 1.2–2.2 mm in anthesis, margins erose; inner tepals loosely appressed in anthesis and fruit, white to pink, ovate to suborbiculate, 1.7–2.9 mm in anthesis, margins erose; filaments dimorphic; anthers yellow or pink; styles and stigmas 0.5–1 mm in anthesis. |
functionally unisexual; filaments dimorphic; anthers pink, orange, or yellow; styles and stigma ca. 0.1 mm in anthesis. |
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Staminate flowers | outer tepals loosely appressed in anthesis, reflexed in fruit, white, broadly elliptic, 0.9–1.8 mm in anthesis, margins entire; inner tepals appressed in anthesis and fruit, white, elliptic, 0.9–1.7 mm in anthesis, margins entire. |
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Pistillate flowers | outer tepals loosely appressed in anthesis, usually reflexed in fruit, white to pink, often drying yellow, broadly elliptic to ovate, 0.5–1.3 mm in anthesis, margins entire; inner tepals appressed in anthesis and fruit, white to pink, often drying yellow or red, broadly elliptic to ovate, 0.6–1.5 mm in anthesis, margins entire. |
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Achenes | included, reddish brown, 3(–4)-gonous, 2.5–4 × 1.3–2.3 mm, shiny, smooth. |
mostly included, brown to yellow-brown, 3-gonous, 1.3–2.1 × 0.7–1.2 mm, shiny, smooth. |
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2n | = 36. |
= 28. |
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Polygonella americana |
Polygonella polygama |
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Phenology | Flowering Jun–Oct. | |||||||||
Habitat | Sandy roadsides, fields, riverbanks, scrub forests, waste places | |||||||||
Elevation | 10-200 m (0-700 ft) | |||||||||
Distribution |
AL; AR; GA; LA; MO; NM; OK; SC; TX
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AL; FL; GA; MS; NC; SC; TX; VA
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Discussion | Varieties 3 (3 in the flora). J. H. Horton (1963) found considerable intergradation among characters used by J. K. Small (1933) to separate Polyonella polygama, P. brachystachya, and P. croomii. He included the latter two taxa in P. polygama. R. P. Wunderlin (1981) as well as G. L. Nesom and V. M. Bates (1984) discussed morphological variation among these geographically distinct entities and recognized three varieties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5, p. 539. | FNA vol. 5, p. 538. | ||||||||
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonella | Polygonaceae > subfam. Polygonoideae > Polygonella | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Gonopyrum americanum | Polygonum polygamum | ||||||||
Name authority | (Fischer & C. A. Meyer) Small: Mem. Torrey Bot. Club 5: 141. (1894) | (Ventenat) Engelmann & A. Gray: Boston J. Nat. Hist. 5: 231. (1845) | ||||||||
Web links |