[*][*] Panicle short or small, loosely spreading or diffuse; perennials.
[+] Sterile flower none; spikelets warty roughened.
10. P. verrucòsum, Muhl. Smooth; culms branching and spreading, very slender (1–2° long), naked above; leaves linear-lanceolate (2–3´´ wide), shining; branches of the diffuse panicle capillary, few-flowered; spikelets dark green, oval, acute, ¾´´ long; lower glume ¼ as long as the faintly nerved second.—Sandy swamps, N. Eng. to Va., near the coast, and southward.
[+][+] Lower (sterile) flower neutral, or in n. 12 and sometimes in n. 11 staminate, the palet scarious and sometimes small and inconspicuous.
[++] Culm-leaves broadly lanceolate or wider, with 9–15 principal nerves (obscure or none in n. 17).
[=] Spikelets 1–1½´´ long.
11. P. xanthophỳsum, Gray. Culm simple, or at length branched near the base (9–15´ high); sheaths hairy; leaves lanceolate, very acute (4–6´ long by ½´ wide), not dilated at the ciliate-bearded clasping base, smooth except the margins, strongly 9–11-nerved; panicle long-peduncled, very simple, the appressed branches bearing a few roundish-obovate spikelets (about 1½´´ long); lower glume ovate, acutish, {1/3}–½ the length of the 9-nerved second.—Dry sandy soil, Maine to Penn., Wisc., Iowa, and northward; rare. June.—Yellowish-green; spikelets minutely downy; sterile flower sometimes staminate.
12. P. latifòlium, L. Culm (1–2° high) smooth; the joints and the throat or margins of the otherwise smooth sheaths often bearded with soft woolly hairs; leaves broadly oblong-lanceolate from a heart-clasping base (often 1´ wide), taper-pointed, 11–15-nerved, smooth, or sparingly downy-hairy; panicle more or less exserted (2–3´ long), usually long-peduncled, the branches spreading; spikelets obovate, 1½´´ long, downy; lower glume ovate, not half the length of the many-nerved second; sterile flower often (not always) with 3 stamens.—Moist thickets; common. June–Aug.
13. P. clandestìnum, L. ([Pl. 13], fig. 6, 7.) Culm rigid (1–3° high), very leafy to the top, at length producing appressed branches, the joints naked; sheaths rough with papillæ bearing very stiff and spreading bristly hairs; leaves oblong-lanceolate from a heart-clasping base, very taper-pointed; lateral and usually also the terminal panicle more or less enclosed in the sheaths, or with the terminal one at length long-peduncled;—otherwise resembling n. 12; but the spikelets more ovoid, often smooth; the lower flower (always?) neutral.—Low thickets and river-banks, N. Eng. to Mich., Mo., and southward. June–Sept.
14. P. víscidum, Ell. Culms stout, upright or ascending, at length much branched, leafy to the top, densely velvety-downy all over, as also the sheaths, with reflexed soft and often clammy hairs, except a ring below each joint; leaves likewise velvety, lanceolate (½´ wide), 11–13-nerved; panicle spreading, the lateral ones included; spikelets obovate, 1 or 1½´´ long, downy; the roundish lower glume scarcely one fourth the length of the 7-nerved second one.—Damp soil, N. J. to Va., and southward. Aug.