SEDGE FAMILY. 



Style 2 cleft; achene lenticular, not 3-angled; scales falling from the rachi* i*--- 

 Achene one-half as long as the scale; umbel nearly or quite simple 

 Spikelets yellow; superficial cells of the achene <>>!. m^ 

 Spikelets green or brown; superficial cells of the achene quadrate 

 Scales obtuse or obtusish, appressed. 



Scales membranous, dull; style much exserted. 

 Scales subcoriaceous, shining; style scarcely exserted. 

 Scales acute, somewhat spreading at maturity. 



Achene narrowly obovate; spikelets %'-i%' long. 

 Achene linear-oblong; spikelets 3"-o." long. 



Achene nearly as long as the scale; umbel sometimes much compound. 

 Style 3-cleft; achene 3-angled. 



Scales falling away from the persistent rachis of tin- flattened npikrlcU. 

 Wiiips of the rachis, if present, permanently adnatt : 



.Scales tipped with recurved awns; low annual, i'-6' tall. 

 Scales acute or obtuse, not awned. 



Wings of the rachis none or very narrow. 



Stamens 3; spikelets linear-oblong, 4"-ia" long; scales acute. 



- 



I. C Jtatvurnt 



a. C di**j. 

 J. C. rivnl.. 



4. C. Smtt. 



l< r.K/..*/ 



'j: i... ,,. 



7. C. imfltxttt. 



ft 111.' 



Annual; culms smooth, 2'-io' long. ft. (' eomttrtttmt. 



Perennial; culms rough, i-2S tall. 9. < 



Stamen i; spikelets ovate, 2"~4" long. 



Tall perennial; achene linear; scales acutish. 10. C fnf*4o9qrthu 



Low annual; achene oblong; scale -tips recurred. n. C. 

 Wings of the rachis distinct. 



Low annual, adventive from Europe; scales brown. 12. L'./tt 

 Tall indigenous perennials (no. 13 sometimes annu.i 



Lower leaves reduced to pointed slu-atha. 13. C. /fai^am. 



Leaves all elongated-linear. 



Scales mucronate, reddish brown or green. 14. C. dtmtalmt. 



Scales acute or obtuse, not mucronate. 



Scales wholly or partly purple brown; achene linear 

 Scales tightly appressed. It C. rotu 



Tips of the scales free. 16. T. tfalln. 



Scales straw-colored; achene obo void 17. <" 



Wings of the rachis separating from it as interior scales; annuals. 



Spikes loose; spikelets 3-10" long. 18. C. 



Spikes dense, cylindric; spikelets i#"-2K" long. 19. C /talft 



Spikelets falling away from the axis of the spikes, the lower pair of scales commonly persists 

 Annuals; spikelets elongated, nearly terete. 

 Scales imbricated; achene obovoid. 



Scales thin, dull brown; spikelets very slender. 

 Scales rigid, yellow-brown ; spikelets stout. ai . 



Scales distant; achene linear-oblong. 22. C. Kngtlmammi 



Perennial by hard, tuber-like basal cornis; spikelets more or less flattened. 

 Achene narrowly linear-oblong, 3-4 times as long as thick. 



Spikelets flat, several-many-flowered. aj. C. itrigot**. 



Spikelets subterete, few-flowered 



Spikelets 6"-i2" long, loosely spicate; lower reflexed. 24. C. rf/m. 

 Spikelets i^"-6" long, densely capitate or spicate. 

 Spikelets all reflexed; culms rough. 



Spikelets spreading or only the lower reflexed; culms smooth 

 Heads oblong or cylindric. 



Spikelets 3"~5 long, the lower reflexed. 

 Spikelets i M -2" long, the lower spreading- 



Heads globose. 

 Achene oblong or obovoid, about twice as long as thick. 

 Rachis wingless or very narrowly winged. 

 Scales pale green, membranous, dull. 

 Scales chestnut-brown, firm, shining. 

 Rachis-wings membranous, broad. 



Scales firm, not appressed; spikelets loosely capitate 



- 



ifm.ni. 







39. C 



< 



Scales thin,' closely appressed; spikelets densely capitate, ja. C. ttk<**l 



i. Cyperus flavescens L,. Yellow 

 Cyperus. (Fig. 543.) 



Cyperus flavescens L. Sp. PI. 46. 1753. 



Annual, culms very slender, tufted, leafy below, 

 3'-i2 r tall, mostly longer than the leaves. Leaves 

 *"-i%" wide, smooth, the longer usually exceed- 

 ing the inflorescence; clusters terminal and sessile 

 or on 1-4 short rays; spikelets in 3's-6's, linear, 

 subacute, yellow, many-flowered, flat, 4 // -9 // lon K- 

 iW-i" broad; scales ovate, obtuse, i-nerved, ap- 

 pressed, twice as long as the orbicular-obovate 

 black obtuse lenticular shining achene; stamens 3; 

 style deeply 2-cleft, its branches slightly exserted; 

 superficial cells of the achene oblong. 



In marshy ground, Maine to Michigan, Florida and 

 Mexico. Also in the Old World. Aug. -Oct. 



