40 CYPERACEAE 



Scale tips not recurved or recurved-awoed. 

 Annuals. 

 Scales fallinji from spikelets. 6. C. erythrorhizos. 



Spikelets fallinji; from rachis. 



Leaves roujihiuarfiined. 7. C. speciosus. 



Leaves smooth-margined. 8. C. ferox. 



Perennials. 

 Spreadinji by tuberiferous stolons. 5. C. esculentus. 



Propagating b\- corm-like basal tubers. 

 Scales j^reen or brownish. 



Spikelets S-tiowered. 10. C. ovularis. 



Spikelets more than 3-flowered. 



Culms rou^h ou the anjiles. 12. C. Bushii. 



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

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



1. C. diandrus 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. Oftnu 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, l'-5' high, growing in 

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

 lets linear-oblong, 2'^-3'^ Jong, 7-13-flowered. — Common on sjind-bars 

 along the Missouri River. June-October. 



4. C. acuminatus Torr. & Hook. Culms 3'-P2' high : spikelets capi- 

 tate or with 1-4 short rays : spikelets oblong, many-llowered. — Exsic- 

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

 Valley. Jul^'-Septemlier. 



5. C. esculentus L. Culms \°-2l° 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-llowered : 

 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'-2i° high : involucral 

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

 numerous, crowded in oblong spikes, 2V'-(i" long, chestnut brown, Hat: 

 scales mucronulate, separating from the axis at maturity. Wingi* of the 

 rachix soon tifpuradng as a pair of liyaliiie 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 spicies, but usually lower: leaves rough-margined : spikelets sub- 

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

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

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

 River. June-October. 



