90 CYPERACEAE (SEDGE FAMILY) 



elaboration, the spikelets or spiculae of authors are called spikes, which they 

 truly are, and they are conglomerated into heads. The genus is an exceedingly 

 critical one and its study should not be attempted with unripe or imperfect 

 specimens. 



I. Spike one, terminal, strictly simple, staminate at the top, or in dioecious plants (4 & 33) 

 all staminate or all pistillate. 



Stigmas three. 



Perigynium spindle-shaped or lanceolate, dark brown or purple . . . .1,2 

 Perigynium short, mostly ovate or elliptic. 

 Perfectly smooth. 



Perigynia 1 to 3, conspicuously spreading, or remote from the staminate portion. 



Obovate, obtuse 8 



Elliptic, sharply beaked 11 



Perigynia several, continuous with the staminate portion. 



Scales leaf-like 9 



Scales short, ciliate 33 



Scales short, entire. 



Very broad, covering the perigynium . . . . . . .10 



Narrower, shorter than the perigynium 12 



Scabrous or hairy. 



Perigynia 1 to 4, scabrous above 3 



Perigynia several to many, hairy ......... 4 



Stigmas two .............. 40 



II. Spikes all aggregated into a round or ovoid uninterrupted head, stigmas two. 



Spikes densely packed, the individual ones scarcely discernible. 

 Head tawny or brown. 



Subtended by 1 or 2 long leafy bracts ......... 67 



Naked or nearly so. 



Perigynium nearly orbicular, dark ......... 57 



Perigynium ovate or lanceolate. 



Spikes staminate at base 63, 64, 65, 66 



Spikes staminate at top. 



Perigynium rough-angled ....... 44, 45, 46, 47 



Perigynium smooth 48, 49, 50, 51 



Head green .............. 45 



Spikes simply aggregated, the individual ones readily recognized. 



Spikes nearly linear, light colored .......... 58 



Spikes oval or ovoid. 



Perigynium wing-margined. 



Broadly ovate or oval .......... 69, 71 



Lanceolate 68, 70 



Perigynium wingless. 



Nerved, beak longer than the body 52 



Nerveless. 



Heads small, globular 50, 51 



Heads oblong ............ 61 



III. Some or all of the spikes distinct. 



Terminal spikes staminate above (staminate flowers inconspicuous), spikes often all 

 approximated into an interrupted head or panicle, stigmas always two. 



Perigynium strongly nerved 52, 53 



Perigynium nerveless or nearly so . . . . . . . 41, 42, 43 



Terminal spike staminate below. 

 Stigmas two. 



Spikes very dark 36, 37, 38, 39 



Spikes tawny or whitish. 

 Perigynium lanceolate. 



Thin and scale-like 68 



More or less thick and rounded. 



Heads fulvous ............ 70 



Heads silvery or silvery-tawny ......... 59 



Perigynium ovate, wing-margined ......... 72 



Perigvnium ovate, not margined ....... 60, 61, 62 



Terminal spike mixed; the intermediate spikes of the tawny interrupted head staminate. 

 Perigynium short and broad, dark-colored ........ 55 



Perigynium ovate or ovate-lanceolate, straw-colored 54 



Terminal spike or spikes entirely staminate. 

 Stigmas two. 



Perigynium strongly nerved ........... 25 



Perigynium nerveless or nearly so. 



all leaf-like ..... 26 



1'iacts not conspicuously leaf-like. 



Spikes rounded or oval. 



Staminate spike short-stalked 21,30,34 



Stjwninsito wpike sessile 36, 37, 38 



