[+] 3. _Vesicariae._ Perigynium smooth and shining, much inflated, at maturity straw-colored or sometimes purple, beaked and conspicuously short toothed (entire in n. 10), usually prominently few nerved, much shorter than in [+] 2; staminate spikes commonly 2 or more; pistillate spikes as a rule long and densely cylindrical.--Sp. 9--16.

[+] 4. _Pseudocyperae._ Perigynium less inflated, more conspicuously nerved or even costate, and with more or less setaceous or awned teeth; scale usually awned; spikes mostly nodding or spreading, comose in appearance, greenish, greenish-yellow, or ochroleucous.--Sp. 17--19.

[+] 5. _Squarrosae._ Perigynium obconic or obovoid, squarrose in exceedingly dense short spikes.--Sp. 20, 21.

[*] 2. Trachychlaenae. Perigynium mostly thick and hard in texture, often scabrous or hirsute, straight-beaked; pistillate spikes compactly flowered, mostly large, erect or nearly so; staminate spikes 1 or more; stigmas 3. Generally large and coa.r.s.e.

[+] 1. _Shortianae._ Terminal spike androgynous, staminate below; perigynium small, scabrous, nearly beakless, entire.--Sp. 22.

[+] 2. _Anomalae._ Terminal spike all staminate; pistillate spikes long and cylindrical, mostly dense; perigynium broad and short, short-beaked, the orifice very slightly notched or entire, mostly granulate.--Sp. 23.

[+] 3. _Hirtae._ A heterogeneous group, distinguished from [+] 2 by the longer and more deeply cut beak (slightly toothed in n. 24), and by the hairy perigynium (smooth in n. 25)--Sp. 24--27.

[+] 4. _Paludosae._ Staminate spikes 2 or more, long stalked; the pistillate 2--several, usually all peduncled, long and heavy, loose-flowered, erect or nodding; perigynium large, thick in texture, strongly nerved, mostly smooth, usually conspicuously beaked. Coa.r.s.e species.--Sp. 28, 29.

[*] 3. Microrhynchae. Parallel with [*] 2; distinguished in general by the much smaller and nearly or entirely beakless and mostly entire-mouthed perigynium, which is much thinner in texture; stigmas 2 or 3. Paludose and alpine species, of various habit, mostly with colored spikes, often in dense tufts or tussocks.

[+] 1. _Atratae._ Terminal spike club-shaped and androgynous with the staminate flowers below (very rarely all staminate in n. 32); pistillate spikes mostly short and dark-colored, erect or drooping; stigmas 3.--Sp.

30--32.

[+] 2. _Rigidae._ Mostly stiff, with short erect closely flowered spikes, an entirely staminate terminal spike, dark colored scales, and bracts with purple or black auricles at base; stigmas 2 or 3.--Sp. 33.

[+] 3. _Acutae._ Mostly larger and more slender, usually paludose, with green or light-colored large and long spikes; stigmas 2 (3 in n. 39).

Distinguished from [+] 2 mainly by habit.--Sp. 34--39.

[+] 4. _Cryptocarpae._ Large, with nodding or drooping large spikes, their dark scales very long and conspicuous; stigmas 2.--Sp. 40, 41.

[+] 5. _Pendulinae._ Distinguished from [+] 4 by the smaller size, smaller spikes, sheathless bracts, and whitish, more or less granulated, nearly pointless perigynium; stigmas 3.--Sp. 42--45.

[*] 4. Hymenochlaenae. Perigynium mostly light green or whitish, usually thin and membranous, often somewhat inflated or loosely investing the achene, commonly smooth and shining (hairy in n. 46, sometimes in n. 47), slender or oblong, attenuate to a distinct or long minutely toothed straight beak (or beakless or nearly so in [+] 1 and n. 55); pistillate spikes several or many, mostly loosely flowered and on filiform nodding or widely spreading peduncles; bracts leaf-like; terminal spike staminate or androgynous; stigmas 3. Mostly rather tall and slender upland species.

[+] 1. _Virescentes._ Terminal spike pistillate at top; pistillate spikes oblong or cylindrical, dense, erect; perigynium ovate or obovate, nearly or quite beakless, often hairy.--Sp. 46, 47.

[+] 2. _Sylvaticae._ Terminal spike all staminate; pistillate spikes mostly long-exserted, slender; perigynium few-nerved, contracted into a cylindrical beak which is longer than the body.--Sp. 48.

[+] 3. _Flexiles._ Terminal spike all staminate; pistillate spikes rather thick (very small in n. 50), more or less drooping; perigynium beaked, few-nerved or nerveless, tawny or whitish.--Sp. 49, 50.

[+] 4. _Debiles._ Terminal spike all staminate (occasionally pistillate above in n. 53); pistillate spikes very narrow and slender, long-exserted and nodding, mostly very loosely flowered; perigynium rather small, not turgid, prominently beaked.--Sp. 51--53.

[+] 5. _Gracillimae._ Terminal spike pistillate at top; pistillate spikes habitually thicker than in [+] 4; perigynium ovate-oblong, more or less turgid; the beak short or none.--Sp. 54--57.

[+] 6. _Griseae._ Terminal spike staminate; perigynium more or less turgid or plump, often glaucous, scarcely beaked, finely striate; spikes erect.--Sp. 58, 59.

[*] 5. Spirostachyae. Perigynium smooth or minutely granulated or rarely somewhat serrate on the margins, prominently nerved, mostly yellowish, squarrose, mostly beaked (entirely beakless in n. 63), the orifice entire; staminate spike mostly single; pistillate spikes 2--5, short (usually 1' long or less), yellow or fuscous, compactly flowered; stigmas 3.--Medium-sized species, growing in meadows and gra.s.sy swales.

[+] 1. _Granulares._ Spikes scattered, cylindrical, the lowest long-stalked; bracts erect, long and leafy; sheaths short or nearly obsolete.--Sp. 60, 61.

[+] 2. _Extensae._ Spikes mostly approximate or aggregated at the top of the culm (becoming remote in C. extensa), the lowest 1 or 2 subtended by a long and leafy mostly abruptly spreading and nearly or entirely sheathless bract. Terminal spike sometimes androgynous.--Sp. 62.

[+] 3. _Pallescentes._ Spikes globular or short-oblong, obtuse, sessile or short-peduncled, approximate at the top of the culm; bracts short, leaf-like, sheathless; perigynium entire at the orifice, the beak none or very short and stout.--Sp. 63, 64.

[*] 6. Dactylostachyae. Perigynium mostly short and triangular, mostly with a short and straight or curved beak, green or greenish, scarcely inflated; scales of the pistillate spikes mostly whitish (sometimes dark-colored in the _Digitatae_), often small; staminate spike mostly one; pistillate spikes short (seldom exceeding 1'), commonly rather loosely flowered and slender (spike single and plant dicious in n. 83); bracts sheathing, the sheaths often conspicuous and colored.--Low and lax or slender species inhabiting meadows and copses.

[+] 1. _Oligocarpae._ Slender and narrow-leaved, with leafy bracts and inconspicuous green sheaths; perigynium rounded on the angles, finely many-striate, often somewhat punctulate as in n. 58, to which the group forms a transition.--Sp. 65--67.

[+] 2. _Laxiflorae._ Slender and more or less broad-leaved, with mostly leafy bracts, green or purple sheaths, and loosely flowered spikes; perigynium mostly conspicuously three-angled, with a more or less curved beak.--Sp. 68--74.

[+] 3. _Paniceae._ Mostly stouter and narrow-leaved, with thinner spikes; perigynium often strongly nerved, not conspicuously triangular, often somewhat turgid; bracts and sheaths various.--Sp. 75--78.

[+] 4. _Bicolores._ Small species with a beakless, more or less round or pyriform perigynium, which is commonly glaucous; terminal spike androgynous or all staminate; stigmas mostly 2.--Sp. 79.

[+] 5. _Digitatae._ Low species; sheaths membranaceous or hyaline and colored, either not prolonged into a bract or the bract very short and not foliaceous; perigynium more or less three-angled, often hairy, the beak straight or nearly so.--Sp. 80--83.

[*] 7. Sphaeridiophorae. Perigynium mostly short and rounded, three-angled in the _Triquetrae_, firm or hard in texture, not inflated, hairy or scabrous, the beak straight and usually bifid; staminate spike one; pistillate spikes short (1' long or less), usually globular or short-oblong, more or less sessile and approximate or the longer ones radical (spike single in n. 84); bracts sheathless, short, or obsolete; stigmas rarely two.--Low species of dry ground, with leaves all radical.

[+] 1. _Scirpinae._ Spike one, unis.e.xual; plant dicious.--Sp. 84.

[+] 2. _Montanae._ Spikes two to several, the lowest occasionally long-peduncled and radical; perigynium rounded, contracted above and below, mostly bearing two prominent ribs, more or less hairy.--Low species of dry soils.--Sp. 85--91.

[+] 3. _Triquetrae._ Taller; spikes mostly approximate at the top of the culm, oblong or cylindrical; perigynium conspicuously 3-angled.--Sp. 92.

[*] 8. Phyllostachyae. Perigynium much as in the _Montanae_; spike one, staminate above; pistillate flowers few, often remote, usually on a more or less zigzag rhachis; scales prolonged and leaf-like.--Sp. 93--95.

[*] 9. Leptocephalae. Perigynium thin in texture, green, oblong or lanceolate or linear in general outline, beakless; spike one, staminate above, thin and slender; stigmas mostly three.--Small, slender and gra.s.s-like.--Sp. 96.

[*] 10. Physocephalae. Spike one, globular or short-oblong, staminate at the apex; perigynium straw-colored, paper-like, more or less inflated; stigmas three. Leaves remarkably broad in our species.--Sp. 97.

-- 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. Acroarrhenae. Staminate flowers borne at the top of the spikes (or, in the _Multiflorae_ and _Arenariae_, spikes often wholly staminate and the plants occasionally dicious).

[+] 1. _Ftidae._ 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. _Vulpinae._ 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. _Multiflorae._ 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. _Arenariae._ 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. _Muhlenbergianae._ 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. _Dioicae._ Spike commonly one, small; plants small and slender, often dicious.--Sp. 115--117.

[*] 12. Hyparrhenae. Staminate flowers borne at the base of the spikes (or in n. 124 and 125 variously situated).

[+] 1. _Elongatae._ 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.