SEDGE FAMILY 



41 



6. FIMBRISTYLIS Vahl. l. F. interior. 



7. ERIOPHORUM L. Cotton-grass. 



Spikelets solitary ; involucre wanting. 

 Plant stoloniferous. 



Glumes purplish-brown with narrow, pale margins. 



Glumes purplish-brown with white, broad margins. 

 Plant tufted, not stoloniferous. 



Upper sheaths inflated ; stem rough above. 



Upper sheaths not inflated; stem smooth. 

 Spikelets several, subtended by foliaceous bracts. 

 Leaf-blades triangular-channeled throughout. 

 Leaf-blades flat, at least below the middle. 



Midrib of the glumes not prominent at the tip of the glume. 



Midrib of the glumes prominent to the very tip. 



8. LEUCOCOMA Ehrh. Alpine Cotton-grass. • i. L. aipina. 



9. SCIRPUS L. Bulrush, Club-rush, Tulb. 



Involucre of a single bract or wanting. 



Spikelets solitary, rarely two together; plants tufted (except No. 5). 



1. S. coloradensis. 



2. S. pauciflorus. 



; bog plants. 



3. S. caespitosus. 



4. S. pumilus. 



Annuals ; stamens 2 ; bristles none. 

 Perennials, with rootstocks. 

 Involucre none. 

 Involucre present, consisting of one erect bract. 



Bract scarcely exceeding the spikelet, often shorter; 

 Bristles 6, longer than the achetaes. 

 Bristles none. 

 Bract at least twice as long as the spikelet; aquatic plants. 



5. S. subterminalis. 

 Spikelets normally more than one, usually several, sometimes numerous. 

 Spikelets few, 1-12, appearing lateral, in a single capitate cluster. 



Annuals, with fibrous roots, tufted; achenes dark, transversely wrinkled. 

 Spikelets obtuse; achenes plano-convex. 6. S. Hallii. 



Spikelets acute; achenes 3-angular. 7. iS. saximontanus. 



Perennials, with rootstocks ; achenes plano-convex, obovate. 

 Stem sharply 3-angled. 



Spikelets acute; bracts long; glumes awned. 8. S. americanus. 



Spikelets obtuse; bracts short; glumes mucronate. 9. S. Olneyi. 

 Stem terete, striate. 10. S. nevadensis. 



Spikelets numeroiis in small clusters of 1-7, arranged in compound umbels; per- 

 ennials with stout rootstocks. 

 Style 2-cleft; achenes obovate and plano-convex, brown. 



Achenes 2 mm. long, nearly as long as the glumes ; spikelets ovoid. 



11. S. validus. 

 Achenes 3 mm. long, distinctly shorter than the glumes; spikelet oblong- 

 cylindric. 12. S. occidentalis. 



Style 3-cleft; achenes obcordate, 3-angled, yellowish. 13. 5. heierochaetus. 

 Involucre of two or more leaves with fiat blades; perennials, with rootstocks. 



Spikelets 3-10, capitate, relatively large. 14. S. paludosus. 



Spikelets numerous, in compoimd umbels or in umbellate heads, relatively small. 

 Bristles downwardly barbed, not much exceeding the fruit. 



Style-branches2;achenesplano-convex;bristlesmostly4. 15. S. microcarpus. 

 Style-branches 3; achenes oblong, 3-angular; bristles 6. 



Plant dark green; glumes acute; achenes pale brown. 16. S. atrovirens. 

 Plantpale;glumesrough-awned:achenesstraw-colored. 17. S. pallidus. 

 Biistles 6, smooth, much exceeding the glmues at maturity; achenes 3-angled. 

 whitish. 

 Spikelets all sessile; glumes brown. 18. S. cyperinus. 



Spilcelets mostlj' pediceled ; glumes mostly greenish black. 19. S. atrocinclus. 



10. HEMICARPHA Nees & Am. 



11. KOBRESIA WiUd. 



12. ELYNA Schrad. 



1. if. aristulata. 

 1. K. bipartita. 

 1. E. Bellardi. 



13. CAREX (Rupp.) L. Sedge.* 



Spike one, androgynous; perigynia glabrous, thin, not margined or triangular, beaked; 

 style withering, not continuous with the achene; stigmas three. 

 Pistfllate scales persistent ; perigynia not stipitate, not becoming reflexed. 

 Spike linear or linear-oblong ; perigynia not infiated. 1 . Nardinae. 



Spike orbicular to short-ovoid; perigynia inflated. 2. Inflatae. 



Pistillate scales deciduous; perigynia stipitate, at least the lower reflexed at maturity. 



3. Athrochlaenae. 

 Spikes one to many; if one, plant not as above. 



Achenes lenticular and stigmas two; lateral spikes sessile; terminal spike partly 

 pistillate, or if staminate, the lateral spikes short, or heads dioecious. 

 Spike one. 



Spike orbicular to short-ovoid. 4. Capitatae. 



Spike linear. 5. Dioicae. 



