202 



CYPERACEAE 



XII. PENDULINAE. 

 XIII. CRYPTOCARPAE. 



XIV. VIRESCENTES. 

 XV. GRACILLIMAE. 



XVI. FLEXILES. 



XVII. DEBILES. 

 XVIII. GRISEAE. 



Pistillate spikes drooping, mostly on slender peduncles (erect in no. 35). 

 Pistillate spilies 0.6-7..5 cm. long : stigmas 3 (2 in no. 30). 

 Pistillate spikes linear : scales shorter than the perigynia. 



XI. PRASINAE. 

 Pistillate spikes globose, oblong or cylindric : 

 scales as long as the perigynia, or longer. • 

 Pistillate spikes 2.,V-10 cm. long : scales 1-8 times 

 as long as the perigynia. 

 Perigvnium tapering to a distinct beak (nearly or quite 

 beakless in nos. 37-41), membranous in texture (firm 

 in no. 50), inflated or loosely investing the achene ; 

 pistillate spikes mostly drooping, often narrowly 

 linear. 

 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 

 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 s'pikes drooping. 

 Perigynia beakless or minutely beaked, finely 

 many-striate : spikes erect or nearly so. 



gg Pistillate spikes small, few-many-flowered, mostly 6-25 

 mm. long (sometimes longer in no. 60). (See also nos. 

 28, 37, 39, 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 



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. 



■ft Spikes solitary, sometimes dioecious. 

 Leaf-blades 2-5 cm. 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. 



XIX. GRANULARES. 



XX. OLIGOCARPAE. 



XXI. LAXIFLORAE. 



XXII. DIGITATAE. 

 XXVII. PHYLLOSTACHYAE. 



XXIII. MONTANAE. 



XXIV. TRIQUETRAE. 



XXV. PHYSOCEPHALAE. 



XXVI. SCIRPINAE. 



XXVII. PHYLLOSTACHYAE. 



XXVIII. LEPTOGEPHALAE. 

 XXIX. 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. 

 Perigynia strongly several-nerved, especially on the outer 



face. 

 Perigvrta 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. 



XXX. VULPINAE. 

 XXXI. MULTIFLORAE. 



XXXII. MUHLENBERGIANAE. 



XXXIII. ELONGATAE. 



XXXIV. OVALES. 



I. LUPULINAE. 



A. Pistillate spikes ovoid or globose, relatively few-flowered. 

 Perigynia subulate, reflexed when mature. 

 Perigynia conic or ovoid, not reflexed. 



Plants yellow or yellowish : perigynia little inflated. 

 Plants green : perigynia well inflated. 

 Perigvnia 6-8 mm. long. 

 Perigynia 12-20 mm. long. 



1. C. CoUiiisii. 



2. C.folliculata. 



3. C. Elliottii. 



