110 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
14. CYPERACEAE. Sedge Family. 
Grasslike or rushlike herbs; stems usually solid; roots fibrous; leaves narrow, with 
closed sheaths, the whole leaf sometimes reduced to a sheath; flowers perfect or 
unisexual, arranged in spikelets, one in the axil of each scale, the spikelets solitary or _ 
clustered, 1 to many-flowered; perianth of bristles or wanting; stamens 1 to 3; styles 
2 or 3; fruit a lenticular or trigonous achene. 
KEY TO THE GENERA. 
Flowers all unisexual, usually in separate spikes. 
Achenes inclosed in a perigynium; glumes 1-flowered. 8. Carex (p. 116). 
Achenes not inclosed in a perigynium; glumes 
2-flowered.... 2... eee eee cc eee eee cece eee 9. Kopresta (p. 124). 
Flowers all, or at least part of them, perfect; spikelets 
similar. 
Scales of the spikelets 2-ranked; spikelets more or less 
flattened .......22 222.222. 2eeeeeeeee ee eee eens 1. Cyperus (p. 110). 
Scales of the spikelets imbricated spirally in several 
ranks; spikelets not flattened. 
Perianth bristles much elongated, woolly......... 7. ER1opHoRuUM (p. 116). 
Perianth bristles short or wanting. 
Spikelets 1 to 4-flowered; plants large, about 
1 meter high, leafy................... 2. CLapium (p. 112). 
Spikelets several to many-flowered; plants 
mostly low. 
Base of the style persistent, enlarged. 
Leaves reduced to sheaths; spikelets 
solitary.......--........2220-- 3. ELEocHarIs (p. 112). 
Leaves not reduced; spikelets several, 
mostly paniculate............ 4. STENOPHYLLUS (p. 114). 
Base of the style deciduous, enlarged or 
narrow. 
Perianth consisting of bristles........ 5. ScrrPus (p. 114). 
Perianth of a single hyaline scale.... 6. HEmIcaRPHA (p. 116). 
1. CYPERUS L. 
Tufted or simple-stemmed annuals or perennials, 50 cm. high or less, with basal 
leaves and triangular stems, the flowers in headlike clusters or unequally branched 
umbels subtended by leaflike bracts; spikelets flattened or cylindric; glumes decid- 
uous, or if persistent the spikelets falling entire, 2-ranked; flowers perfect; perianth 
none; stamens | to 3; achene without a tubercle. 
KEY TO THE SPECIES. 
Annual; plants small, 5 to 15 cm. high; tips of the bracts subulate, 
conspicuously reflexed; inflorescence capitate............. 1. C. inflerus. 
Perennials (rarely annual); plants taller, more than 15 cm. high; 
tips of the bracts mostly erect, rarely spreading; inflores- 
cence various. 
Spikelets ovate to ovate-oblong (4 to 5 mm. long, crowded at 
the ends of the rather long, subequal rays of the umbel). 2. G. cyrtolepis. 
Spikelets linear to narrowly oblong. 
Spikelets narrowly oblong; scales of the flowers not over- 
lapping, especially in fruit (very strongly nerved). 
Inflorescence crowded, subcapitate.................. 3. C.fendlerianus. 
