Panicum philadelphicum |
Panicum gymnocarpon |
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panic de philadelphie, Philadelphia panic grass, Philadelphia witchgrass |
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Habit | Plants annual; hirsute, hairs papillose-based, usually yellow-green to green, sometimes purplish. | Plants perennial; forming extensive colonies by their long, decumbent, sprawling basal branches and stolons. | ||||||||
Culms | 8-100 cm tall, about 1 mm thick, erect to decumbent, simple to profusely branched; nodes sparsely to densely pilose. |
60-130 cm, thick, glabrous, rooting profusely at the lower nodes; nodes glabrous, often with a dark green band. |
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Sheaths | usually shorter than the internodes, glabrous, prominently veined; ligules 0.5-1.5 mm; blades 15-40 cm long, 7-25 mm wide, tapering from midlength, flat, both surfaces glabrous, bases subcordate, margins scabrous to smooth, widest at the base, apices acute. |
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Leaves | often crowded basally; sheaths rounded, usually longer than the internodes, hispid, hairs papillose-based, to 5 mm; ligules 0.5-1.5 mm; blades 3-30 cm long, 2-12 mm wide, linear, ascending to erect, flat, hirsute to sparsely pilose, greenish or purplish, bases truncate to subcordate and ciliate on the margins, apices acute. |
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Panicles | 7-27 cm long, 4-24 cm wide, 1/4 - 1/3 as long as the plants, diffuse, usually exserted at anthesis, not breaking at the base of the peduncles to become a tumbleweed; rachises glabrous or sparsely pilose basally; primary branches spreading, secondary branches and pedicels confined to the distal 2/3 secondary branches diverging to appressed, with 1-4 spikelets; pedicels 3-15 mm, spreading to appressed, scabrous or hirsute; pulvini glabrous or pilose. |
10-40 cm long, 7-20 cm wide, open, with straight, rigid rachises; branches whorled, stiffly ascending, with short, appressed, higher order branches; ultimate branchlets 1-sided, with solitary spikelets or small clusters of spikelets; pedicels 0.1-1.5 mm. |
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Spikelets | 1.4-2.4 mm long, 0.5-0.7 mm wide, usually green, glabrous. |
5.5-7 mm long, about 1 mm wide, narrowly lanceoloid, glabrous. |
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Glumes | spreading apart at maturity, keeled, prominently veined, scabrous along the midveins; lower glumes nearly as long as the lower lemmas; upper glumes and lower lemmas 3-veined, spreading, greatly exceeding the upper florets, lower lemmas longer than the upper glumes, arcuate; lower florets sterile; lower paleas thin; upper florets 1.9-2.2 mm, less than 1/3 as long as the spikelets, obovoid, lustrous, pale to brownish, acute, often short-stipitate. |
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Lower glumes | 0.5-0.9 mm, usually less than 1/2 as long as the spikelets, 3-4-veined, truncate to acuminate; upper glumes 1.6-2 mm, 7-veined, veins not prominent; lower lemmas 1.6-1.9 mm, 7-9-veined, veins not prominent; lower paleas absent; lower florets sterile; upper florets 1.5-1.7 mm long, about 0.4 mm wide, often dark brown, sometimes disarticulating, apices minutely papillose. |
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2n | = 18. |
= 40. |
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Panicum philadelphicum |
Panicum gymnocarpon |
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Distribution |
AL; AR; CT; DC; DE; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; NC; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; NB; NS; ON; QC
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Discussion | Panicum philadelphicum grows in open areas such as fallow fields, roadside ditches, receding shores, and rock crevices. It is restricted to the eastern part of the Flora region. It intergrades with P. capillare, possibly as a result of hybridization, especially in the southeastern United States. Seeds germinating on receding shores in late summer often produce tiny plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Panicum gymnocarpon grows in swamps, wet woodlands, and the marshy shores of lakes and streams. It is also found occasionally in shallow water, often in the shade. It is restricted to the United States. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 25, p. 459. | FNA vol. 25, p. 485. | ||||||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Phanopyrum > sect. Phanopyrum | ||||||||
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Subordinate taxa | ||||||||||
Synonyms | P. tuckermanii | Phanopyrum gymnocarpon | ||||||||
Name authority | Bernh. ex Trin. | Elliott | ||||||||
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