§ 2. VIGNEA. Staminate flowers few and inconspicuous, borne at the base or apex of the pistillate spikes. Pistillate flowers in short sessile spikes (or spike single in some cases), which are commonly more or less aggregated into heads or even panicled. Perigynium plano-convex. Styles two and achene lenticular.—The spikes, especially the uppermost, usually have contracted bases when the staminate flowers are borne below the pistillate ones, and empty scales at the top when the staminate flowers are borne at the summit.
[*] 11. Acroarrhenæ. Staminate flowers borne at the top of the spikes (or, in the Multifloræ and Arenariæ, spikes often wholly staminate and the plants occasionally diœcious).
[+] 1. Fœtidæ. Spikes tawny or brown, not elongated, very densely aggregated into a continuous globose somewhat chaffy head; perigynium ovate or ovate-lanceolate, nerveless or nearly so, mostly thin in texture.—Sp. 98, 99.
[+] 2. Vulpinæ. Spikes mostly yellow or tawny when mature, densely aggregated or sometimes somewhat scattered below or even panicled; perigynium thick in texture, spongy at base, mostly stipitate, bearing very conspicuous nerves, which converge below and are especially prominent on the outer side.—Sp. 100–102.
[+] 3. Multifloræ. Heads various, mostly loosely flowered, sometimes a panicle, yellow or tawny; spikes short (rarely longer than broad), staminate flowers sometimes occupying whole spikes in the middle or at the apex of the head; perigynium mostly small and short and nearly nerveless, or in some species becoming nearly lanceolate and more or less prominently nerved, firm in texture, usually numerous.—Sp. 103–108.
[+] 4. Arenariæ. Spikes longer than in the last section, linear or nearly so, aggregated into short, almost globose heads; perigynium lanceolate or ovate-lanceolate, mostly larger and more delicate in texture; scales awn-pointed or very acute. Staminate flowers variously situated.—(C. arenaria.)
[+] 5. Muhlenbergianæ. Spikes green or nearly so when mature, aggregated or scattered, never in compound heads; perigynium mostly short-ovate, staminate flowers always at the top of the spike.—Sp. 109–114.
[+] 6. Dioicæ. Spike commonly one, small; plants small and slender, often diœcious.—Sp. 115–117.
[*] 12. Hyparrhenæ. Staminate flowers borne at the base of the spikes (or in n. 124 and 125 variously situated).
[+] 1. Elongatæ. Spikes silvery green or sometimes tawny when mature, distinct, mostly small; perigynium not wing-margined nor conspicuously broadened, mostly nearly flat on the inner surface.—Sp. 118–124.