Panicum verrucosum |
Panicum rigidulum |
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warty panicgrass |
redtop panic grass, redtop panicum, smooth witchgrass |
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Habit | Plants annual; weak, ascending or sprawling. | Plants perennial; cespitose, not rhizomatous, occasionally purple-tinged throughout, mostly glabrous throughout (except as noted). | ||||||||||||||||
Culms | 10-150 cm, slender, wiry, erect at first, ultimately decumbent, sprawling, glabrous, often with purple dots and streaks, branching extensively at the base, rooting at the lower nodes. |
35-150 cm, stout, compressed. |
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Sheaths | often shorter than the internodes, loose, glabrous, margins short-ciliate; ligules 0.2-0.5 mm, membranous, erose, ciliate; blades 5-20 cm long, 3-10 mm wide, thin, flat, glabrous on both surfaces, margins scabridulous, apices long-acuminate. |
more or less strongly compressed or keeled, sides usually glabrous or sparsely pubescent distally; ligules 0.3-3 mm, membranous, erose or ciliate, cilia often themselves fimbriate; blades 8-50 cm long, 2-12 mm wide, flat or folded, both surfaces usually glabrous or scabridulous, or the adaxial surfaces sparsely pilose basally. |
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Panicles | 5-30 cm, nearly as wide as long; branches few, capillary, with a few spikelets distally; pedicels 0.5-10 mm. |
terminal and axillary, 9-40 cm, 1/3 – 3/4 as wide as long, usually dense; ultimate branchlets usually appressed, 1-sided, scabridulous; pedicels 0.5-1.5 mm, usually appressed, sometimes with 1-several slender hairs at the apices. |
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Spikelets | 1.7-2.2 mm long, about 1 mm wide, ellipsoid or obovoid, glabrous, faintly veined, subacute or obtuse at the apices. |
usually 1.6-3.8 mm, usually subsessile, lanceolate, green, purple-tinged, or purple, glabrous. |
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Lower glumes | 0.3-0.8 mm, reduced, acute; upper glumes and lower lemmas subequal or the glumes shorter, distinctly verrucose, with hemispheric warts; upper florets 1.6-2 mm long, about 1 mm wide, grayish-brown, dull, minutely papillose, acute. |
2/5 – 3/4 as long as the spikelets, 3-veined, midveins keeled; upper glumes and lower lemmas subequal or the glumes slightly longer, often spreading slightly apart at the apices, midveins keeled, usually scabridulous apically; lower florets sterile; lower paleas to 2/3 as long as the lower lemmas; upper florets 1.4-2 mm long, 0.6-0.8 mm wide, 2/5 – 3/4 as long as the spikelets, occasionally stipitate, lustrous, with a tuft of minute, thickish hairs at the apices; upper lemmas thick, stiff, clasping the upper paleas throughout their length. |
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2n | = 36. |
=18. |
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Panicum verrucosum |
Panicum rigidulum |
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Distribution |
AL; AR; CT; DC; DE; FL; GA; IL; IN; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; WV
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AL; AR; CA; CT; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MO; MS; NC; NH; NJ; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WI; WV; PR; BC; NS; ON |
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Discussion | Panicum verrucosum grows primarily in open, moist or wet sandy areas bordering swamps, marshes, or lakes or on roadside ditches; it also grows occasionally in open, drier woodlands. It is restricted to the eastern United States and is mostly, but not exclusively, coastal. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Panicum rigidulum grows in swamps, wet woodlands, flood-plain forests, wet pine savannahs, marshy shores of rivers, ponds, and lakes, drainage ditches, and other similar wet to moist places; it is rarely found in dry sites. Its range extends from southern Canada to Mexico, Guatemala, and the Antilles. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 25, p. 487. | FNA vol. 25, p. 477. | ||||||||||||||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Phanopyrum > sect. Verrucosa | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Agrostoidea > sect. Agrostoidea | ||||||||||||||||
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Subordinate taxa | ||||||||||||||||||
Synonyms | P. debile | |||||||||||||||||
Name authority | Muhl. | Bosc ex Nees | ||||||||||||||||
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