Cyperaceae 83 
FF. Leaves not glaucous; perigynia plainly beaked; pistillate scales often erose 
at tip.c -C- C. polymorpha Muhl. 
DD.  Pistillate spikes 8—12 mm. long. 
G. Pistillate scales light-colored. W. E. 
C. hendersoni Bail. 
GG.  Pistillate scales black, white-veined. 
H. Perigynia smooth, straw-colored, very short-beaked. C. E. 
C. heteroneura Boott 
HH. Perigynia granular, brownish or green, beakless. 
I. Perigynia brownish; stem exceeding the leaves. C. 
C. stylosa Mey. 
II. Perigynia green; stem exceeded by the leaves. C. (C. spreta.) 
C. accedens Holm 
GROUP 6 
A. Pistillate scales green or black or purple. 
B. Perigynia granulate, faintly veined; pistillate spikes 8—25 mm. long. W. E. 
C. lenticularis Michx. 
BB.  Perigynia smooth. 
C. Perigynia veinless or faintly veined. 
D.  Pistillate spikes 0.4—1 cm. long. C. E. 
C. alpina Sw. 
DD. Pistillate spikes 1—6 cm. long. 
E. Plant robust; most of the bracts exceeding the stem; pistillate scales 
acute. E. C. aquatilis Willd. 
EE. Plant slender; only the lower bract if any exceeding the stem; pistillate 
scales obtuse. 
F. Leaves somewhat revolute when dry; lower spikes short-stalked. CC. 
E. (C. acutina tenuior. ) 
C. acutina Bail. 
FF. Leaves somewhat involute when dry; lower spikes long-stalked. W. 
Car. (C. tolmieit and varieties. ) 
C. scopulorum Holm 
CC. Perigynia strongly veined; pistillate spikes 8—30 mm. long. E. (C. 
nebraskensis ultriformis.) C. nebraskensis Dew. 
AA. Pistillate scales yellowish. 
G. Perigynia shorter than the scales; pistillate scales acuminate. W. E. 
C. bovina How. 
GG. Perigynia equaling or longer than the scales; pistillate scales acute or cuspi- 
date or short-awned. W.C. E. (C. aurea celsa.) 
C. aurea, Nutt. 
: GROUP 7 
A. Perigynia granulate or papillose, the margins not serrulate. 
B.  Pistillate spikes 3—5 cm. long; pistillate scales dark-purple; perigynium-beak 
emarginate; perigynia green or purple-spotted. C. E. 
C. pachystoma, Holm 
BB.  Pistillate spikes 0.5—1.5 cm. long. 
C. Pistillate scales dark-purple; perigynium-beak entire; perigynia brown. W. 
C. decidua Boott 
CC. Pistillate scales black; perigynium-beak emarginate; perigynia brownish- 
green with purple spots. E. 
C. prionophylla Holm 
