Panicum philadelphicum

Bernh. ex Trin.
Common names: Philadelphia witchgrass
Endemic
Synonyms: Panicum tuckermanii
Treatment appears in FNA Volume 25. Treatment on page 459.

Plants annual; hirsute, hairs papillose-based, usually yellow-green to green, sometimes purplish. Culms 8-100 cm tall, about 1 mm thick, erect to decumbent, simple to profusely branched; nodes sparsely to densely pilose. 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. 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. Spikelets 1.4-2.4 mm long, 0.5-0.7 mm wide, usually green, glabrous. 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. 2n = 18.

Distribution

Conn., N.J., N.Y., Del., D.C., Wis., W.Va., N.B., N.S., Ont., Que., Tex., N.C., S.C., Ark., Kans., Okla., Tenn., Pa., Va., Mass., Maine, N.H., R.I., Vt., Ill., Ga., Ind., Iowa, Md., Ohio, Mo., Minn., Mich., Ky., Ala.

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.

Selected References

None.

Key

1 Spikelets less than 1/2 as wide as long; plants purplish Panicum philadelphicum subsp. lithophilum
1 Spikelets usually more than 1/2 as wide as long; plants green or yellow-green. > 2
2 Spikelets 1.9-2.4 mm long; apices of the upper glumes and lower lemmas straight; secondary branches and pedicels divergent; blades often 6-12 mm wide, those of the flag leaves usually more than 1/2 as long as the panicles Panicum philadelphicum subsp. gattingeri
2 Spikelets 1.4-2.1 mm long; apices of the upper glumes and lower lemmas curving over the upper florets at maturity; secondary panicle branches and pedicels appressed; blades usually 2-6 mm wide, those of the flag leaves usually less than M as long as the panicles Panicum philadelphicum subsp. philadelphicum

"decumbent" is not a number."-11-veined" is not declared as a valid unit of measurement for this property.

... more about "Panicum philadelphicum"
puberulent +
papillose +
anatomy +  and kranz +
Robert W. Freckmann +  and Michel G. Lelong +
Bernh. ex Trin. +
1 (?) +  and 3 (?) +
keeled +  and rounded +
divergent +  and parallel +
intravaginal +, extravaginal +, branching +  and basal +
truncate +  and subcordate +
swelling +
membranous +
disarticulating +  and pseudopetiolate +
non-radiate +  and radiate +
purplish +  and greenish +
3 cm30 mm <br />0.03 m <br /> (30 cm300 mm <br />0.3 m <br />) +
hirsute +  and sparsely pilose +
filiform +  and ovate flat +
0.2 cm2 mm <br />0.002 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
spikelike +
0 cm0 mm <br />0 m <br /> (1 cm10 mm <br />0.01 m <br />) +
not developed +
terete +  and compressed +
thick-walled +
sometimes longer +
Philadelphia witchgrass +
small green +
simple +  and profusely branched +
8 cm80 mm <br />0.08 m <br /> (100 cm1,000 mm <br />1 m <br />) +
erect +  and decumbent +
not compressed +
2 cm20 mm <br />0.02 m <br /> (300 cm3,000 mm <br />3 m <br />) +
woody +  and not succulent +
1 cm10 mm <br />0.01 m <br /> (?) +
Conn. +, N.J. +, N.Y. +, Del. +, D.C. +, Wis. +, W.Va. +, N.B. +, N.S. +, Ont. +, Que. +, Tex. +, N.C. +, S.C. +, Ark. +, Kans. +, Okla. +, Tenn. +, Pa. +, Va. +, Mass. +, Maine +, N.H. +, R.I. +, Vt. +, Ill. +, Ga. +, Ind. +, Iowa +, Md. +, Ohio +, Mo. +, Minn. +, Mich. +, Ky. +  and Ala. +
capillary +
germination +
pistillate +  and staminate +
sometimes longer +
compressed +  and terete +
shorter or longer +
subtending +
pubescent +  and glabrous +
tuberculate +
unequal +
membranous +
well-developed +
papillose-based +
purplish +, usually yellow-green +  and green +
uncinate +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Oval (?) +  and Round (?) +
bracteate +  and ebracteate +
hollow +  and solid +
coriaceous +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
membranous +
inconspicuous +
truncate +  and acuminate +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.19 cm1.9 mm <br />0.0019 m <br />) +
complex +  and simple +
concealed +  and prominent +
2 +  and 1 +
7cm +  and 27cm +
subterranean +
1/4 +  and 1/3 +
pyramidal +
4 cm40 mm <br />0.04 m <br /> (24 cm240 mm <br />0.24 m <br />) +
simple +  and compound +
spreading +  and appressed +
hirsute +  and scabrous +
0.3 cm3 mm <br />0.003 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
dry +  and fleshy +
pilose +  and glabrous +
pilose +  and glabrous +
diverging;appressed +
usually longer +
in triplets +  and paired +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.24 cm2.4 mm <br />0.0024 m <br />) +
unisexual +  and bisexual +
ellipsoid +  and lanceoloid +
0.1 cm1 mm <br />0.001 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.5mm +  and 0.7mm +
1 +  and 3 +
compound +  and simple +
fused +  and free +
2 +  and 3 +
dome--shaped +  and triangular +
Panicum tuckermanii +
Panicum philadelphicum +
Panicum sect. Panicum +
species +
membranous +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (?) +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
pubescent +  and glabrous +
rugose +  and verrucose +
chartaceous-indurate +  and rigid +
not prominent +
aquatic +  and terrestrial +
dioecious +, monoecious +  and synoecious +