CYPERACEAE (SEDGE FAMILY) 



173 



wings to the hollow of the joint of the axis next below), deciduous when old. 

 Stamens 1-3. Style 2-3-cleft, deciduous. Achene lenticular or triangular, naked 

 at the apex. — Culms mostly triangular, simple, leafy at base, and with one or 

 more leaves at the summit, forming an involucre to the umbel or head. 

 Peduncles or rays unequal, sheathed at base. All flowering in late summer or 

 autumn. {Kviretpos, the ancient name.) 



§ 1. Scales deciduous, readily falling away from the somewhat persistent 

 rhachilla of the flattened spikelet a. 

 a. Style 2-cleft : achene lenticular, laterally compressed (the edge turned 

 to the rhachilla) : rhachilla narrow, not winged ; annuals b. 

 b. Achenes much shorter than the subtending scales c. 

 c. Achenes orbicular, with narrowly oblong superficial cells . 

 c. Achenes obovate or narrower, the superficial cells broad d. 

 d. Achenes oblong-obovate e. 



e. Spikelets lance-oblong ; scales marked yn\h dark brown or 

 purple, or merely greenish. 

 Stamens 2 ; style-branches conspicuously exserted . 

 Stamens 8 ; style-branches scarcely exserted 

 6. Spikelets lance-linear ; scales oblong, yellow or yellowish- 

 brown throughout ; stamens 2 



d. Achenes linear-oblong or clavate ; scales ovate or oblong. 



Spikelets brownish. 1.5-2 mm. broad 



Spikelets greenish, about 1 mm. broad 



b. Achenes nearly as long as the subtending scales .... 

 a. Style 3-cleft : achene trigonous /. 

 f. Annuals g. 



g. Scales ta{)ering to recurved slender tips 



g. Scales without recurved tips h, 



h. Scales 2.5-3.5 ram. long 



h. Scales 2 mm. or less long i. 

 i. Spikelets in globose heads ; rhachilla wingless or only ob- 

 scurely winged. 

 Spikelets green or whitish-brown, oblong; scales acute 

 Spikelets reddish-brown or purplish, linear ; scales blunt 



or barely mucronate 



i. Spikelets in cylindric or elongate heads ; rhachilla bearing 



freely deciduous scale-like wings 



/. Perennials, the bases hardened and corm-like or stoloniferous j. 

 j. Scales stronglj' several-ribbed ; achenes 2-3 mm. long. 

 Spikelets in oblong or narrowly obovoid heads 



Spikelets in globose or subglobose heads 



J. Scales faintlj' few-nerved or nerveless ; achenes less than 2 men. 

 long k. 

 Culms naked or nearly so, the lower sheath nearly or quite 



bladeless 



Culms leafy below I. 



I. Plant not stoloniferous; rhachilla wingless ; stamen 1 . 

 I. Plant looselv stoloniferous ; scales decurrent on the rhachilla 



as wings ; stamens 3 m. 

 m. Achenes short-obovoid ; scales with free or spreading 

 mucronate tips 



1. C. fla/oescena. 



2. C. diandrus. 



3. C. rivularis. 



4. C. NuUallii. 



5. C. mic7'odoniu8. 



6. C. Gaiesii. 



T. C.flavicomus 



8. C. Aristat/us. 



9. C. compressus. 



11. C. acuminatus. 



13. C. fuscus. 



19. C. erythrorhisos. 



10. C. Schweinitsii. 

 34. C.filiculmis. 



k. 



14. C. haspan. 



12. C. pseudovegefus. 



15. C. deniaius. 



scales appressed, 



§2. 



n. 



It. 



of the umbel, or 1 

 much overtopping 



m. Achenes linear- to oblong-cylindric 

 blunt or barely mucronate n. 

 Scales chestnut-color. 

 Involucre shorter than the rays 



bract slightly longer 

 Involucral bracts numerous and 

 the umbel 



Scales straw-color or pale brown 



Rhachillas of the spikelets soon breaking away from the main rhachis ; 



the .scales falling only in extreme age o. 

 ). Annuals. 



Flowers remote, the successive scales not reaching the bases of 

 the ones above on the same side ...... 



Flowers approximate, the successive scales overlapping the bases 



of those above 



?. Perennials, with hard corm-like bases p. 



p. Spikelets very strongly flattened 



p. Spikelets terete, subterete. or only slightly flattened q. 

 q. Spikelets reflexed. in thick cylindric or obovoid heads r. 

 r. Culms smooth and glabrous. 



Spikelets loosely spicate ; achenes 2.5-3 mm. long 

 Spikelets den.^ely spicate and overlapping ; achenes less 

 than 2.5 mm. long. 

 Spikelets 3-(i-fl()wpred. linear-cylindric, not rigid 

 Spikelets 1-2 dowered, subuLte, rigid .... 



16. C. rotundus. 



17. C. HaUii. 



18. C. esculentus. 



21. C. Engelmanni, 

 20. C.ferax. 



22. C. strigosus. 



23. C. refracUiB. 



24. C lancasfriensis. 



25. C. Jiystricinus. 



