196 CyPERACEAE 



leaflike bracts; spikes usually peduncled, sometimes sessile; spikelets sessile, 1- to many-flowered; flowers bisexual; scales usually 

 2-ranked; perianth none; stamens 1-3; style continuous with the ovary, not enlarged at base, deciduous; stigmas 2 or 3; achenes 

 lenticular or 3-angled. About 700 species, mostly in tropical and warm-temperate regions of both hemispheres. 



lA. Stigmas 2 ; achenes lenticular. 



2A. Achenes dorsiventrally compressed, the ventral surface facing the rachilla 1. C. serotinus 



2B. Achenes laterally compressed, the angle facing the rachilla. 

 3A. Spikelets many-flowered, not jointed at base. 



4A. Surface cells of the achene longitudinally oblong, thus the achene transversely wrinkled 2. C. diaphanus 



4B. Surface cells of the achene hexagonal, thus the achene puncticulate. 



5A. Culms decumbent or ascending at base, often producing roots at the nodes; scales distinctly sulcate 3. C. sanguinolentus 



5B. Culms erect; scales not sulcate. 



6A. Scales 3.5-5 mm. long, with a curved keel 4. C. unioloides 



6B. Scales 1.5-2.5 mm. long, with a straight keel. 



7A. Spikelets usually almost erect, gradually tapering to the apex, partially tinged with dark red; achenes narrowly oblong, 



subtruncate 5. C. polystachyos 



7B. Spikelets usually spreading, linear (parallel-sided), brownish or dark brown; achenes oblong-obovate, not truncate. 



6. C. globosus 



3B. Spikelets 1 -flowered, jointed at base, in a dense terminal globose head; rhizomes long-creeping 7. C brevijoUus 



IB. Stigmas 3; achenes trigonous (Nos. 25-28, sometimes the stigmas 2 and achenes lenticular). 

 8A. Rachilla articulate; spikelets hardly flattened. 



9A. Rachilla articulate only at base; spikelets 4-5 mm. long 8. C. cyperoides 



9B. Rachilla articulate below each scale; spikelets 1—1.5 cm. long 9. C. odoratus 



8B. Rachilla not articulate; spikelets usually flattened. 

 lOA. Spikelets spicate, the rachis distinct. 



11 A. Rhizomes long-creeping; culms not tufted. 



12A. Culms long-leaved at base; subtending bracts longer than or nearly as long as the inflorescence. 



13A. Rachis hispid; scales broadly ovate, 2 mm. long; plant of wet places 10. C. pilosus 



13B. Rachis not hispid; scales narrowly ovate, 3-3.5 mm. long; plant of sandy places 11. C rotundus 



12B. Culms with bladeless or short-bladed sheaths at base; subtending bracts shorter than the inflorescence. . . 12. C. monophyllus 

 IIB. Rhizomes thick and very short, or absent; culms tufted. 



14A. Culms stout, thickened at base; perennials or apparently annuals. 



15A. Scales elliptic or ovate, acute or mucronate; achenes elliptic or narrowly ovate. 



16A. Spikelets scarcely flattened, 4-6 mm. long; scales acute 13. C. ohwii 



16B. Spikelets compressed, 5-8 mm. long; scales with a short recurved mucro at apex 14. C. exaltatus var. iwasaXii 



15B. Scales narrowly oblong, obtuse; achenes narrowly oblong 15. C. glomeratiis 



14B. Culms slender, not thickened at base; annuals or biennials. 



17A. Scales 1-1.5 mm. long, rounded and emarginate or mucronate, nearly as long as the achene. 



18A. Rachis ciliate; scales sanguineous, entire 16. E. orthostachyus 



18B. Rachis glabrous; scales light yellow to reddish brown, mucronate. 



19A. Rachis and rachilla nearly wingless; scales light yellow, minutely mucronate 17. C. iria 



19B. Rachis and rachilla winged; scales distinctly mucronate. 



20A. Scales light yellow to tawny with a straight mucro 18. C. microiria 



20B. Scales reddish brown, the mucro of the scale awnlike, more or less recurved 19. C. amuricus 



17B. Scales, including the short awn, 3-3.5 mm. long, rather obtuse, nearly 3 times as long as the achene. . . 20. C. compressus 

 lOB. Spikelets fascicled or digitate, the rachis wanting; small annuals or perennials. 

 21A. Spikelets distinctly compressed; scales acutely keeled, always 2-ranked. 



22A. Achenes nearly as long as the scale, acutely 3-angled; scales dark sanguineous or blackish brown, rounded and slightly 



emarginate, not mucronate 2 1 . C. difformis 



22B. Achenes 54"/^ 3S long as the scale, obtusely angled, whitish; scales pale to reddish brown, mucronate. 

 23A. Scales obtuse with an extremely short mucro, often partially reddish. 



24A. Scales straight; rachilla quite or almost hidden by the densely imbricate scales 22. C. haspan 



24B. Scales ultimately recurved; rachilla distinctly visible 23. C. tenuispica 



23B. Scales rounded or truncate, the midrib pale green, excurrent into a long recurved awn 24. C. hakpnensis 



2 IB. Spikelets terete or slightly flattened; scales 2-ranked or spiral, obtusely keeled, pale green. 



25A. Achenes ellipsoidal or obovoid, obtusely angled; scales ovate or ovate-orbicular, several-nerved. 



26A. Scales ovate-orbicular, obtuse 25. C niigatensis 



26B. Scales ovate, rather acute or gradually pointed 26. C. nipponicus 



25B. Achenes oblong or lanceolate, acutely angled or winged; scales oblong to lanceolate, hyaline, 3- to 5-nerved. 



27A. Scales 2-ranked, with a smooth or sparsely spinulose mucro; achenes acute but not winged 27. C. extremiorientalis 



27B. Scales spirally arranged or inconspicuously 2-ranked, with a smooth or minutely papillose mucro; achenes narrowly 

 winged 28. C. pacifictts 



1. Cyperus serotinus Rottb. C. japonicus Miq.; Juncel- rays, subtended by 3 or 4 spreading leaf like bracts; spikes 2-4 



lus serotinus (Rottb.) C. B. Clarke; Duval-jouvea serotina cm. long and as broad, the rachis usually appressed-setulose; 



(Rottb.) Palla; C. ma\inoi Nakai ^Mizu-gayatsuri. Rhi- spikelets 1-2 cm. long, 2-2.5 mm. wide, turgid-biconvex, dark 



zomes elongate, terminated by an oblong tuber; culms 50-100 sanguineous to pale green; scales broadly ovate, 2-2.5 mm. 



cm. long, stout, usually smooth; leaves 5-8 mm. wide; long, obtuse, not keeled, entire, involute; achenes 1.5 mm. 



corymbs compound, large, with 5-8 erect-spreading smooth long, nearly orbicular, biconvex, dorsiventrally compressed, 



