Fimbristylis dichotoma |
Fimbristylis puberula |
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fork fimbry |
hairy fimbry |
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Habit | Plants perennial, cespitose, (10–) 20–80 cm, base thickened, not bulbous; rhizomes absent. | Plants perennial, mostly loosely cespitose, to 100 cm, bases swollen; rhizomes short, knotty, or scaly, slender, contorted. | ||||
Culms | sometimes solitary, narrowly linear, distally angular, glabrous. |
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Leaves | nearly distichous, spreading to ascending, 1/2 length of culms; sheaths distally ciliate, backs mostly glabrous; ligule line of short hairs; blades narrowly linear, 2–3 mm wide, flat to broadly involute, scabridciliate, adaxially smooth or hirtellous. |
ascending, from 1/3 as long to equally as long as culms, glabrous to pubescent; sheaths apically ciliate; ligule essentially absent or (in rhizomatous individuals) present, complete or incomplete; blades narrowly linear, 1–2 mm wide, mostly strongly involute, scabrid-ciliate. |
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Inflorescences | anthelae compound, dense or open, ascending-branched, longer than broad; scapes slender, 1 mm wide, slightly compressed distally; proximalmost involucral bract exceeding anthela. |
anthelae simple or compound, compact or diffuse, mostly broad, ascending-branching; scapes slender, wandlike, 1 mm thick; lower leafy involucral bracts exceeded by or exceeding panicle. |
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Spikelets | pale drab brown to chestnut brown, ovoid-lanceoloid, 4–8 mm; fertile scales broadly oblong or ovate, 2 mm, acute to obtuse angled, glabrous, midrib reaching scale tip or excurrent, finely mucronate. |
variously red-brown, broadly ovoid to lance-cylindric, 5–10 mm; fertile scales broadly ovate, obtuse or obtuse-angled, 2.5–3.5 mm, abaxially glabrous or variously puberulent, midrib excurrent as mucro. |
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Flowers | stamens 1–2; styles 2-fid, flat, fimbriate. |
stamens 3; styles 2-fid, flat, fimbriate. |
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Achenes | white to brownish, lenticular, obovoid, 1–1.2 mm, cancellate, each face longitudinally with (5–)10–12 ribs, connected by vertical rows of horizontally rectangular pits. |
yellowish to dark brown, lenticular-obovoid, 1 mm, with 11–20 vertical lines of horizontally rectangular or isodiametric, distinct or indistinct pits. |
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2n | = 20, 30. |
= 20. |
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Fimbristylis dichotoma |
Fimbristylis puberula |
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Phenology | Fruiting summer–fall, into winter southward. | |||||
Habitat | Moist, usually sandy waste areas, roadsides, low fields, and savannas | |||||
Elevation | 0–200 m (to 2000 m, tropics) (0–700 ft (to 6600 ft, tropics)) | |||||
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; South America; Atlantic Islands; Pacific Islands; Indian Ocean Islands; West Indies; Africa; Eurasia; Bermuda; Australia [Introduced in North America]
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AL; AR; AZ; DE; FL; GA; IL; IN; KS; KY; LA; MD; MI; MO; MS; NC; NE; NJ; NM; NY; OH; OK; SC; TN; TX; UT; VA; ON
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Discussion | Fimbristylis dichotoma is found in temperate to tropical regions worldwide. It is one of the most widespread and weedy species of Fimbristylis, unquestionably with many races and forms. The two commonest forms in the United States often occur in mixed populations, one sort with inflorescence branches more ascending, inflorescence dense, habit lower, and leaves broader; the other sort usually taller, inflorescence more sparse, branches more widely spreading, and leaves more ascending and narrower. The abundance of such plants both in regions where rice originated and in regions where rice is, or was, introduced, indicates an Asian origin for such weeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 125. | FNA vol. 23. | ||||
Parent taxa | Cyperaceae > Fimbristylis | Cyperaceae > Fimbristylis | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Scirpus dichotomus, F. annua var. diphylla, F. brizoides, F. diphylla subsp. diffusa, F. glauca, F. polymorpha, Scirpus diphyllus | Scirpus puberulus | ||||
Name authority | (Linnaeus) Vahl: Enum. Pl. 2: 287. (1805) | (Michaux) Vahl: Enum. Pl. 2: 289. (1805) | ||||
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