Panicum amarum |
Panicum rigidulum |
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bitter beachgrass, bitter panicgrass, bitter panicum |
redtop panic grass, redtop panicum, smooth witchgrass |
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Habit | Plants perennial; rhizomatous, rhizomes stout, glabrous and glaucous throughout. | Plants perennial; cespitose, not rhizomatous, occasionally purple-tinged throughout, mostly glabrous throughout (except as noted). | ||||||||||||||||||||
Culms | 20-250 cm tall, 3-10 mm thick, erect or decumbent, simple or branched from the lower nodes; nodes glabrous; internodes glabrous, glaucous. |
35-150 cm, stout, compressed. |
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Sheaths | shorter or longer than the internodes, not keeled, glabrous; collars often glaucous and purplish; ligules 1-5 mm; blades 7-50 cm long, 2-13 mm wide, erect or ascending, firm, thick, flat basally, more or less involute towards the apices. |
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 | 10-80 cm long, 2-17 cm wide, contracted, slightly nodding; primary branches whorled or opposite, strongly ascending to appressed; pedicels 0.5-15 mm, appressed to slightly divergent. |
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 | 4-7.7 mm long, 1.5-2 mm wide, narrowly ovoid, glabrous, acuminate; lower florets staminate. |
usually 1.6-3.8 mm, usually subsessile, lanceolate, green, purple-tinged, or purple, glabrous. |
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Glumes | and lower lemmas relatively thick; lower glumes 2.8-4 mm, 1/2 - 4/5 as long as the spikelets, 3-9-veined, apices of the midveins sometimes scabridulous; upper glumes and lower lemmas extending 1.5-3 mm beyond the upper florets, apices stiffly gaping; upper glumes 3.9-7.6 mm, 5-9-veined; lower lemmas slightly shorter than the upper glumes, 7-9-veined, lower paleas 3-7 mm, oblong-hastate, folded over the anthers; lower florets staminate; upper florets 2.4-3.9 mm long, 1-1.8 mm wide, narrowly ovoid to oblong, glabrous, smooth, shiny, lemma margins clasping the paleas only at the base. |
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Lower | glumes 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, 54. |
=18. |
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Panicum amarum |
Panicum rigidulum |
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Distribution |
AL; CT; DE; FL; GA; LA; MA; MD; MS; NC; NJ; NM; NY; PA; RI; SC; 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 amarum grows in the coastal dunes, wet sandy soils, and the margins of swamps, along the Atlantic Ocean and the Gulf of Mexico from Connecticut to northeastern Mexico. It is also known, as an introduction, from a few inland locations in New Mexico, North Carolina, and West Virginia, as well as in the Bahamas and Cuba. (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. 472. | FNA vol. 25, p. 477. | ||||||||||||||||||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Repentia | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Agrostoidea > sect. Agrostoidea | ||||||||||||||||||||
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Name authority | Elliott | Bosc ex Nees | ||||||||||||||||||||
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