48 CYPERACEAE 



sylvania : Chester ; Erie ; Jefferson ; Northampton ; Franklin ; 

 Lancaster ; Lackawanna ; York ; Lehigh. 



17. Scirpus Eriophonun Michx. (Man. p. i8o. ) In swamps, Newf. 

 to Ont., Fla. and La. — Pennsylvania : Lancaster; Cumberland, 



18. Scirpus atrocinctus Fernald. Blackish Wool-grass. (Man. p. 

 1045.) Newf. to Saskatchewan, Pa. and Iowa. — Pennsylva7tia : Monroe. 



6. ELEOCHARIS R. Br. 



Spikelet scarcely or not at all thicker than the scape : scales mostly leathery. 



1. E. ntu/ata. 

 Spikelet usually manifestly thicker than the scape : scales mostly membra- 

 nous. 



Style-branches or stigmas 2 : achene lenticular or biconvex. 



Upper sheath scarious, hyaline : plants perennial by slender rootstocks. 



2. E. olivacea. 

 Upper sheath truncate, oblique or toothed, not scarious. 



Annuals with fibrous roots. 

 Perianth-bristles longer than the achene : spikelet ovoid. 



3. E. obtusa. 

 Perianth -bristles not longer than the achene, often short or wanting : 



spikelet cylindric. 4. E. Engelmannii. 



Perennials with horizontal rootstocks. 

 Tubercle flat-conic. 

 Scape and spike stout. 5. E. palu^tris. 



Scape and spike slender. 6. E. glaucescens. 



Tubercle swollen, bulb-like : spikelet not thicker than the scape. 



7. E. Sntallii. 

 Style-branches or stigmas 3 : achene 3-angled or turgid. 

 Achene cancellate. 

 Achene longitudinally ribbed. 8. E. acicularis, 



Achene not longitudinally ribbed. 9. E. tuberculosa. 



Achene smooth, papillose, or irregxilarly ridged-reticulated. 

 Tubercle plainly distinguishable from the achene. 



Achenes with the 3 angles ribbed. 10. E. tricostata. 



Achenes obtusely 3-angled. 

 Scapes slender to nearly filiform : scales obtuse. 



i\. E. tenuis. 

 Scapes flattened : scales acute. 12. E. acuminata. 



Tubercle long-conic, scarcely distinguishable from the achene. 

 Scapes filiform, 1-2.5 dm. long : spikelet 4-6 mm. long. 



13. E. intermedia. 

 Scapes flattened, 3-6 dm. long : spikelet 7-13 mm. long. 



14. E. roslellata. 



1. Eleocharis mutata (L. ) R. & S. Qu.\drangular Spike-rush. 

 (Man. p. 168; I. F. /. 575.) In wet places, N. J. to Mich., Ala., Mo., 

 Tex. and Guatemala. Also in the W. I. and S. Am. — Pennsylvania : 

 Philadelphia ; Erie. 



2. Eleocharis olivacea Torn Bright-green Spike-rush. (Man. 

 p. 168; I. ¥. f.381.) In wet soil, Me. to Ont. and S. C, mostly near 

 the coast. — Pennsylvania: Luzerne, Lily Lake. 



