[++][++] Hispid or hairy on the sheaths, at least the lower; spikelets mostly scattered on slender pedicels in an ample, loose, at length very effuse panicle; culms mostly branched from the base, erect or ascending (10–20´ high).
3. P. capillàre, L. (Old-witch Grass.) ([Pl. 13], fig. 4, 5.) All the sheaths and usually the leaves copiously hairy or hispid; panicle mostly very compound, the branches divaricate when old; spikelets from ovoid to narrowly oblong, pointed; lower glume half the length of the upper empty one, which is longer than the elliptical obtuse perfect flower.—Sandy soil and cultivated fields everywhere. Aug.–Oct.—Varies extremely in size and appearance, the culms erect and simple, or decumbent, geniculate and branched; in depauperate forms the spikelets only ¾´´, in the larger forms 1½´´ in length.
4. P. autumnàle, Bosc. Root perennial (?), lower sheaths and margins of the small narrow leaves more or less hairy, otherwise glabrous, except some bristly hairs in the main axils of the very effuse capillary panicle, its much elongated divisions sparingly branched, or even simple and terminated with solitary spindle-shaped spikelets; lower glume minute; perfect flower lanceolate-oblong and pointed, nearly equalling the lance-oblong obtusish empty glumes.—Sand-hills, Ill. to Minn., Mo., and southward.
[+][+] Sterile flower rudimentary (staminate in n. 7), its glume fully twice the length of the lower glume; spikelets small (1 or 1½´´ long); root perennial.
5. P. ánceps, Michx. Culms flat, upright (2–4° high); leaves rather broadly linear (1–2° long, 4–5´´ wide), smooth; panicle contracted-pyramidal; spikelets ovate-lanceolate, pointed, a little curved; second glume 5–7-nerved; neutral flower one third longer than the perfect one.—Wet sandy soil, N. J. and Penn. to S. Ill., and southward. Aug.—Spikelets larger and branches of the panicle longer and narrower than in the next.
6. P. agrostoìdes, Muhl. Culms flattened, upright (2–4° high); leaves long, and with the sheaths smooth; panicles terminal and often lateral, pyramidal (4–8´ long); spikelets racemose, crowded and one-sided on the spreading branches, ovate-oblong, acute (purplish); second glume 5-nerved, longer than the neutral flower; perfect flower shorter, bearded at the apex.—Wet meadows and shores, E. Mass. to Minn., Neb., and common southward. Aug.
7. P. Curtísii, Chapm. Culms stout, 3–4° high, often rooting below; mostly glabrous; panicle slender, simple, spike-like (6–8´ long), the spikes appressed; spikelets lanceolate, acute; lower glume half the length of the 5-nerved second one.—Ponds, Del. to Fl. and Tex.
[+][+][+] Sterile flower staminate; lower glume more than half the length of the next; spikelets large (2–2½´´ long), ovate, pointed, as are the glumes, etc.; perennials, glabrous, with tall or stout and rigid upright culms.
8. P. virgàtum, L. ([Pl. 13], fig. 8, 9.) Tall (3–5° high); leaves very long, flat; ligule silky-bearded; branches of the compound loose and large panicle (9´–2° long) at length spreading or drooping; spikelets scattered, usually purplish.—Moist sandy soil; common. Aug.
9. P. amàrum, Ell. Culms (1½° high or more) sheathed to the top; leaves involute, glaucous, coriaceous, the uppermost exceeding the contracted panicle, the simple racemose branches of which are appressed; spikelets pale.—Sandy shores, Conn., Va., and southward. Aug., Sept.—The northern form (var. mìnus, Vasey & Scribn.) somewhat smaller than the southern.