[*] Spikes erect; the rhachis filiform and nearly terete.
1. P. filifórme, L. Culms very slender (1–2° high), upright; lower sheaths hairy; spikes 2–8, alternate, approximate, filiform; spikelets oblong, acute (½´´ long); lower glume almost wanting.—Dry sandy soil, Mass. to N. J. along the coast, to Iowa, Neb., and southward. Aug.
[*][*] Spikes spreading; the rhachis flat and thin.
P. glàbrum, Gaudin. Culms spreading, prostrate, or sometimes erect (5–12´ long), glabrous; spikes 2–6, widely diverging, nearly digitate; spikelets ovoid (about 1´´ long); upper empty glume equalling the flower, the lower almost wanting.—Cultivated grounds and waste places; common, especially southward; sometimes appearing indigenous. Aug., Sept. (Nat. from Eu.)
P. sanguinàle, L. (Common Crab- or Finger-Grass.) ([Pl. 13], fig. 1–3.) Culms erect or spreading (1–2° high); leaves and sheaths glabrous or hairy; spikes 4–15, spreading, digitate; spikelets oblong (1½´´ long); second glume half the length of the flower, the lower one small.—Cultivated and waste grounds. Aug.–Oct. (Nat. from Eu.)
§ 2. PANICUM proper. Spikelets scattered, in panicles, awnless.
[*] Panicle elongated and racemose, wand-like or pyramidal; the numerous and usually pointed spikelets short-pedicelled, excepting n. 3 and 4.
[+] Sterile flower none; lower glume short; spikelets ½–1½´´ long; annuals except n. 4; leaves flat; sheaths flattened.
[++] Glabrous and smooth throughout; spikelets appressed, short-pedicelled.
2. P. prolíferum, Lam. Culms usually thickish and rather succulent, branched, geniculate and ascending from a procumbent base; sheaths flattened; ligule ciliate; panicles terminal and lateral, compound, pyramidal, the slender primary branches at length spreading; spikelets pale green, rarely purplish; lower glume broad, {1/3} to ¼ the length of the upper, which is little longer than the flowering one.—Marshy river-banks and shores, especially if brackish, but also in the interior, from Mass. to Iowa, and southward. Aug.