96 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



5. Eleocharis olivacea Torr. 



Boggy soil; Holmead Swamp and about the reservoir near Howard University. 

 July-Sept. Me. to N . C. and Mich . 



6. Eleocharis flaccida (Reichenb.) Urban. 



In shallow water and mud flats; Hunting Creek. Coastal Plain from N. J. south- 

 ward. (E. ochreata Steud.) 



7. Eleocharis engelmanni Steud. 



Muddy ground; south of Washington; infrequent. June-Aug. Mass. to Mo. 



8. Eleocharis obtusa (Willd.) Schult. 



Mud flats and moist stream borders; common, especially to the east and south. 

 May-Sept. Eastern and northern U. S. 



9. Eleocharis palustris (L.) Roem. & Schult. 



In shallow water or open marshy ground; Fourmile Run; Dyke; Ead's Mill: op- 

 posite Alexandria. May-July. Throughout the U. S. 

 9a. Eleocharis palustris glaucescens (Willd.) A. Gray. 



Alluvial flats; infrequent; Little Falls and southward. May-June. Throughout the 

 U.S. 



More slender than the species. 



10. Eleocharis quadrangulata (Michx.) Roem. & Schult. 



In shallow water; along Eastern Branch; rare. July-Sept. Eastern and middle 

 states. (E. mutata of Britt. & Brown, Tllustr. Fl.) 



5. STENOPHYLLUS Raf. 



1. Stenophyllus capillaris (L.) Britton. 



Common in sandy open ground and fields. July-Sept. Throughout the U. S. 

 (Fimbristylis capillaris A. Gray.) 



6. FIMBRISTYLIS Vahl. 



Achenes triangular, smooth ; umbel decompound 1. F. mucronulata. 



Achenes lenticular, strongly reticulate; umbel simple or nearly so. .2. F. baldwiniana. 



1. Fimbristylis mucronulata (Michx.) Blake. 



Common in low, moist, sandy or alluvial soil, mostly near streams. July-Oct. East- 

 ern U. S. (F. autumnalis of authors, not Roem. & Schult.) 



2. Fimbristylis baldwiniana Torr. 



Alluvium; Great Falls, Maryland. Aug. Atlantic Coastal Hain and lower Missis- 

 sippi Valley. (Included in F. laxa in Gray's Manual.) 



7. SCIRPUS L. 



Involucral bract 1 , appearing like a continuation of the culm, or wanting. 

 Involucral bract wanting; spikelets solitary. Plants leafy, densely tufted, perennial, 



15-20 cm. tall 1. S. planifolius. 



Involucral bract developed, erect; spikelets 2 to many, rarely 1. 



Culms sharply 3-angled; 2 or 3 leaf blades well developed 4. S. americanus. 



Culms terete; sheaths bladeless. 



Plants annual, slender, rarely 50 cm. tall; spikelets 1-6, in a close head. 

 Achenes turgid, biconvex; bristles 6, barbed, about equaling the achene. 



2. S. debilis. 

 Achenes plano-convex; bristles 1 or 2 smooth rudiments or none. 



3. S. smithii. 

 Plants perennial, robust, commonly 2 meters tall; spikelets numerous, in a 



drooping umbel 5. S. validus. 



