CYPERACEAE 
Pistillate spikes drooping, mostly on slender peduncles (erect in no. 35). 
Pistillate spikes 0.6-7.5 em. long: stigmas 3 (2 in no. 30). 
Pistillate spikes linear: scales shorter than the perigynia. 
XI. PRASINAE. 
. PENDULINAE. 
Pistillate spikes globose, oblong or cylindric: 
scales as long as the perigynia, or longer. 
Pistillate spikes 2.5-10 cm. long: scales 1-8 times 
as long as the perigynia. 
Perigynium tapering toa distinct beak (nearly or quite 
beakless in nos. 37-41), membranous in texture (firm 
in no. 50), inflated or loosely investing the achene ; 
pene spikes mostly drooping, often narrowly 
inear. 
Terminal spike staminate below, pistillate above: 
beak of the perigynium short or none. 
Spikes all erect or nearly so. 
Pistillate spikes drooping or spreading (erect or 
i little spreading in no. 42). 
Terminal spike entirely staminate, or sometimes pis- 
tillate at the base. - 
Leaves pubescent. 
Leaves glabrous. 
Perigynia manifestly beaked, nerved or nerve- 
less: pistillate spikes drooping. 
Perigynia beakless or minutely beaked, finely 
many-striate: spikes erect or nearly so. 
22 Pistillate spikes small, few-many-flowered, mostly 6-25 
mm. long (sometimes longer in no.60). (See also nos. 
28, 37, 89, 40, 44, 51-54.) 
Perigynia glabrous. 
Pistillate spikes many-flowered, 6-25 mm. long, usu- 
ally dense. 
Pistillate spikes few-several-flowered, often loose. 
Scales of the spike normal, neither elongated nor 
Jeaf-like. 
Leaf-blades 2-36 mm. wide: bracts leaf-like, usu- 
ally large. 
Perigynia finely many-striate. 
Perigynia with few or many, mostly strong, 
nerves. 
Leaf-blades and stems mostly capillary: bracts 
mere bladeless sheaths. 
_ Scales of the spikes elongated, leaf-like. 
Perigynia pubescent. 
Perigynia mostly rounded. 
Perigynia conspicuously 3-angled. 
tt Spikes solitary, sometimes dioecious. 
Leaf-blades 2-5 em. wide, leathery. 
Leaf-blades 0.5-6 mm. wide, not leathery. 
Staminate and pistillate flowers on different scapes. 
Staminate and pistillate flowers in the same spike. 
Scales of the spikes elongated, leaf-like. 
Scales of the spikes short, normal. 
Perigynia obtuse : swamp species. 
Perigynia beaked: prairie species. 
XVII. 
AVIE 
XIX. 
XXV. 
XXVI. 
XXVII. 
XXVIII. 
XXIX. 
CRYPTOCARPAE. 
. VIRESCENTES. 
. GRACILLIMAE. 
. FLEXILES. 
DEBILES. 
GRISEAE. 
GRANULARES. 
OLIGOCARPA E. 
. LAXIFLORAE. 
DIGITATAE. 
PHYLLOSTACHYAE, 
. MONTANAE. 
TRIQUETRA E. 
PHYSOCEPHALAE. 
SCIRPINAE. 
PHYLLOSTACHYAE. 
LEPTOCEPHALAE. 
FILIFOLIAE. 
B. Staminate flowers few, at the summits or bases of the always sessile spikes, or sometimes forming 
whole spikes, or variously intermixed with the pistillate: stigmas always 2: achene lenticular, 
compressed, ellipsoid or plano-convex. VIGNEA. 
Staminate flowers at the summit of the spike. 
Spikes yellowish or brown at maturity, in compound or pan- 
icled clusters. 
bap Sore strongly several-nerved, especially on the outer 
ace. 
Perigymia nerveless or faintly nerved. 
Spikes green or greenish when mature, aggregated or sepa- 
rated, in simple clusters. 
Staminate flowers at the bases of the spikes, variously inter- 
mingled with the pistillate in the spikes, or occasionally 
forming whole spikes. 
Perigynia wingless, the inner face flat. 
Perigynia with narrow or broad marginal wings, the inner 
face concave. 
I. LUPULINAE. 
A. Pistillate spikes ovoid or globose, relatively few-flowered. 
Perigynia subulate, reflexed when mature. 
<a conie or ovoid, not reflexed. 
Plants yellow or yellowish: perigynia little inflated. 
Plants green: perigynia well inflated. 
Perigynia 6-8 mm. long. 
Perigynia 12-20 mm. long. 
XXX. 
XXXI. 
XXXII. 
XXXIII. 
XXXIV. 
VULPINAE. 
MULTIFLORAE. 
MUHLENBERGIANAE. 
ELONGATAE. 
OVALES. 
1. C. Collinsii. 
2. C. folliculata. 
3. C. Elliottii. 
