40 CYPERACEAE 



Scale tips not recurved or recurved-awned. 

 Annuals. 

 Scales falling from spikelets, 

 Spikelets falling from raohis. 

 Leaves rough- margined. 

 Leaves smooth-margined. 

 Perennials. 

 Spreading by tuberiferous stolons. 

 Propagating by corm-like basal tubers. 

 Scales green or brownish. 

 Spikelets 3- flowered. 

 Spikelets more than 3-flowered. 

 Culms rough on the angles. 

 Culms almost smooth on the angles. 

 Scales yellow or straw-colored. 



1. C. dlandrus Torr. Annual, 2''-12'' high with about thre'e leaves to 

 the involucre : spikelets sessile or on short rays, linear-oblong, many- 

 flowered : scales brownish, membranous and dull : aohene oblong, not 

 shining, its superficial cells quadrate. — Along streams. Often abundant 

 on sand-bars along the Missouri River. June-October. 



2. C. rlvularis Kunth. Closely resembles the last but the styles are 

 scarcely exserted, and the scales are subcoriaceous and shining. — Wet, 

 grassy places. More or less common throughout. June-October. 



3. C. inflexus Muhl. Sweet-smelling annual, l'-5' high, growing in 

 dense clumps : spikelets in close heads or with a few short rays : spike- 

 lets linear-oblong, 2''-3" long, 7-13-flowered. — Common on sand-bars 

 along the Missouri River. June-October. 



4. C. acuminatus Torr. & Hook. Culms 3'-12'' high : spikelets capi- 

 tate or with 1-4 short rays : spikelets oblong, manj-flowered. — Exsic- 

 cated places. — Locally abundant. Dodson, Greenwood, Lake City, Grain 

 Valley. July-September. 



5. C. esculentus L. Culms l°-2i° high : umbel 4-10-rayed, the rays 

 much shorter than the longest of the involucral leaves : spikelets some- 

 what flattened, straw-colored, in loose spikes 4"-6" long, many-flowered : 

 scales nerved with acute, rather loose tips. — In low grounds. Frequent, 

 especially on sand-bars along the Missouri River. June-October. 



6. C. erythrorhizoa Muhl. Culms tufted, 3'-2P high : involucral 

 leaves 3-7, much longer than the rays of the compound umbel : spikelets 

 numerous, crowded in oblong spikes, 2\"~Q" long, chestnut-brown, flat : 

 scales mucronulate, separating from the axis at maturity. Wings of the 

 raehis soon separating as a pair of hynUne scales. — Along streams. Ex- 

 tremely abundant on sand-bars along the Missouri River. May-October. 



7. C. speciosus Vahl. In general appearance much resembling the 

 last species, but usually lower : leaves rough-margined : spikelets sub- 

 terete, linear, many-flowered, 3"-12'' long, dull-brown, 1" or less wide: 

 raehis broadly-winged, the wings clasping the ackene : scales obtuse, over- 

 lapping, thin, dull-brown. — Common on sand-bars along the Missouri 

 River. June-October. 



