CYPERACEAE. 59 



Bristles present, longer than the achenes. 3. 5. caespitosus. 



Bristles wanting. 4. 5'. pumilis. 



Spikelets normally more than one, usually several or many ; taller plants. 

 Spikelets few, 1-12, appearing lateral. 



Annual with fibrous roots. 5. 5. Hallii. 



Perennial with rootstocks. 6. 5. aniericanus. 



Spikelets numerous, umbellate. 7. S. lacustre. 



Involucre of 2 or more leaves with flat blades. 



Spikelets few, umbelled or capitate, relatively large. 8. S. campestris. 



^ Spikelets numerous, in compound umbels or in umbelled heads, relatively small. 

 Style-branches 2 ; achenes plano-convex ; bristles mostly 4. 



9. 5. rubrotinctus. 

 Style-branches 3; achenes 3-angular; bristles 6. 10. 5'. atrovirens. 



1. Scirpus coloradensis Britt On muddy shores of lakes in northern Colo. 

 — Alt. about 5000 ft. — Larimer Co. 



2. Scirpus pauciflorus Lightf. In wet soil from Anticosti to B. C, N. Y. 

 and Calif. — Alt. 9500-11,500 ft. — Antonito; Seven Lakes; Ruxton Dell; 

 Georgetown. 



3. Scirpus caespitosus L. In bogs and among wet rocks from Greenl. to 

 Alaska, N. C. and Colo.; also Europe and Asia. — Lat. 39°-4i°.* 



4. Scirpus pumilus Vahl. In wet places in alpine regions in Alb. and Colo. 

 — " Rocky Mountains." 



5. Scirpus Hallii A. Gray. In wet soil from Mass. to Colo., Fla. and Tex. ; 

 also Mex. — Locality not given. 



6. Scirpus americanus Pers. {S. pimgens Vahl.) In fresh and alkaline 

 swamps from Me. to B. C, Fla. and Calif. — Alt. 4000-6500 ft. — Plains and 

 foot-hills near Boulder; Julesburg; mesas near Pueblo; Colorado Springs; 

 Lake City; Spring Canon; Platte River, Denver; Fort Collins. 



7. Scirpus lacustris L. In lakes and swamps from Newf. to B. C, Fla. 

 and Calif. — Alt. 4000-8500 ft. — Gypsum, Eagle Co.; Walsenburg; Ft. Col- 

 lins ; Grand Junction ; Buffalo Pass, Park Range ; New Windsor, Weld Co. ; 

 near Ft. Collins. 



8. Scirpus campestris Britton. {S. maritimus of Coult. Man.) In wet 

 places, especially with alkaline soil, from Man. to Wash., Tex. and Ariz. ; 

 also Mex. — Alt. 4000-6500 ft. — Ft. Collins ; New Windsor, Weld Co. ; Mont- 

 rose ; Walsenburg ; Grand Junction ; lowland along Poudre River ; Ft. Collins. 



9. Scirpus rubrotictus Fernald. In swamps from Newf. to Ida., N. Y. and 

 Colo. — Alt. 4000-8000 ft. — McCoy; La Veta; Steamboat Springs, Routt Co. 



10. Scirpus atrovirens Muhl. In swamps from N. Sc. to Sask., Ga. and 

 La. and Colo. West of Man. and Nebr. it is only represented by v. pallidus 

 Britt. — Alt. 4000-6000 ft. — Plains and foot-hills near Boulder; Ft. Collins; 

 New Windsor, Weld Co.; along Poudre River, Ft. Collins. 



5. ELEOCHARIS R. Br. Spike-rush. 



Style-branches 2. 



Annuals with fibrous roots. 1. E. atropurpurea. 



Perennials with horizontal rootstock. 



Culm stout ; tubercle conic-triangular. a. E. palustris. 



Culm slender; tubercle narrower. 3- E. glaucescens. 



* Hall & Harbour, who collected in Colorado, did not give any definite locali- 

 ties. On the labels is only given: Rocky Mts., lat. 39°-4i°. 



