Panicum philadelphicum |
Panicum philadelphicum subsp. philadelphicum |
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panic de philadelphie, Philadelphia panic grass, Philadelphia witchgrass |
panic de philadelphie |
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Habit | Plants annual; hirsute, hairs papillose-based, usually yellow-green to green, sometimes purplish. | Plants often slender, pilose, yellowish-green. | ||||||||
Culms | 8-100 cm tall, about 1 mm thick, erect to decumbent, simple to profusely branched; nodes sparsely to densely pilose. |
erect or decumbent. |
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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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Blades | 2-6 mm wide, often erect, those of the flag leaves usually less than 1/2 as long as the panicles. |
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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. |
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Spikelets | 1.4-2.4 mm long, 0.5-0.7 mm wide, usually green, glabrous. |
1.4-2.1 mm, ovoid-ellipsoid, pale green to slightly reddish. |
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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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Upper glumes | and lower lemmas hooked over the upper florets; mature upper florets more than 1/2 as wide as long, shiny, blackish, with several pale veins. |
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Secondary | panicle branches usually appressed; pedicels usually short, appressed. |
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2n | = 18. |
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Panicum philadelphicum |
Panicum philadelphicum subsp. philadelphicum |
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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 philadelphicum subsp. philadelphicum grows in meadows, open woods, sand, and on receding shores. Plants with decumbent culms, glabrous pulvini, flexuous pedicels without hairs over 0.2 mm long, spikelets 1.4-1.7 mm long, and the mature floret not disarticulating have been called Panicum tuckermanii Fernald. They are often fairly distinct on receding lake shores in New England and the Great Lakes area (Darbyshire and Cayoutte 1995), but intergrade with subsp. philadelphicum elsewhere. (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. 460. | ||||||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum | Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum > Panicum philadelphicum | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | P. tuckermanii | P. philadelphicum var. tuckermanii | ||||||||
Name authority | Bernh. ex Trin. | unknown | ||||||||
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