40 CYPERACEAE 



Scale tips not recurved or recurved-awned. 

 Annuals. 



Scales falling from spikelets. 6. C. erythrorhizos. 



Spikelets falling from rachis. 



Leaves rough -margined. 7. C. speciosus. 



Leaves smooth-margined. 8. C. ferox. 



Perennials. 



Spreading by tuberiferous stolons. 5. C. esculentus. 



Propagating by corm-like basal tubers. 

 Scales green or brownish. 



Spikelets 3-flowered. 10. C. ovularis. 



Spikelets more than 3-flowered. 



Culms rough on the angles. 12. C. Bushii. 



Culms almost smooth on the angles. 11. C. JUuulmis. 

 Scales yellow or straw-colored. 9. C. strigosus. 



1. C. diandms Torr. Annual, 2 / -12 / high with about three leaves to 

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

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

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

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



2. C. rivularis 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, i?-& high, growing in 

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

 lets linear-oblong, 2 // -3 // long, 7-1 3-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, many-flowered. Exsic- 

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

 Valley. July-September. 



5. C. esculentus L. Culms l-2^ 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 X/ -6 X/ 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. erythrorhizos Muhl. Culms tufted, 3 x -2^ 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 

 rachis soon separating as a pair of hyaline 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 sptcies, but usually lower : leaves rough-margined : spikelets sub- 

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

 rachis broadly-winged, the wings clasping the achene : scales obtuse, over- 

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

 River. June-October. 



