92 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



3. Elymus virginicus L. Terrell orass. 

 Low ground and open woods; frequent. July. Eastern U. S. 



A form with narrower, less distinctly bowed-out glumes has been called E. glabriflo- 

 rus Scribn. & Ball. 

 3a. Elymus virginicus hirsutiglumis (Scribn.) Hitchc. 



Moist places; rare; along the Potomac. Aug. Northern states, south to Va. 



4, Elymus australis Scribn. & Ball. 



Rocky woods; frequent above the fall line along the Potomac. July. Southern 

 states, north to Conn. 



56. HYSTRIX Moench. 

 1. Hystrix pa tula Moench. Bottle-brush. 



Rocky wooded slopes; frequent. July. Eastern U. S. (Gymnostichwm hystrix 

 Schreb.; //. hystrix Millsp.) 



The slender glaucous culms aud pale, horizontally spreading spikelets stand out 

 against the dark background of the wooded slopes, forming a charming picture. 



57. ARUNDINARIA Michx. 



1. Arundinaria tecta (Walt.) Muhl. Small cane. 



Swamps or moist soil; near Ammendale, and beyond our limits between Washington 

 and Baltimore. Southern states, north to Md. 



17. CYPERACEAE. Sedge Family. 



Achene inclosed in a membranaceous sac (the perigynium). Flowers unisexual; 

 plants perennial.... 13. CAREX. 



Achene not inclosed in a perigynium. 

 Flowers unisexual, the staminate and pistillate spikelets crowded in the same in- 

 florescence; achenes white, bony, globular 12. SCLERIA. 



Flowers perfect; achenes not bonelike. 

 Spikelets flat, the flowers 2-ranked. 

 Inflorescence axillary; achene beaked; bristles longer than the achene. 



3. DULICHIUM. 

 Inflorescence terminal; achene beakless; bristles none. 



Spikelets several to many-flowered 1. CYPERUS. 



Spikelets 1-flowered, sessile in a small compact head or glomerule. 



2. KYLLINGA. 



Spikelets terete, the flowers spirally imbricate. 



Spikelets with lor 2 beaked achenes. Bristles present. .11. RYNCHOSPORA. 

 Spikelets with several to many achenes. 

 Culms leafless, terete or flattened; spikelet solitary, terminal. 



4. ELEOCHARIS. 

 Culms leafy (the leaves sometimes bladeless) ; spikelets few to many, if solitary 

 the spikelet lateral. 



Perianth of 1 or more flat scales; bristles present or wanting. 

 Achene and scales stipitate; bristles 3; plants perennial. 9. FUIRENA. 

 Achene and solitary minute scale sessile; bristles wanting; minute 



tufted annual .10. HEMICARPHA. 



Perianth wanting or of bristles only. 



Bristles wanting. Achenes minutely reticulate; inflorescence umbellate. 

 Achene with a minute tubercle, 3-angled: blades capillary. 



5. STENOPHYLLUS. 

 Achene not tuberculate; blades flat or concave.. .6, FIMBRISTYLIS. 

 Bristles present. Plants perennial. 

 Bristles few (1-8), not long and silky, usually not exceeding the scales. 



7. SCIRPTJS. 

 Bristles numerous, long and silky, much exceeding the scales. 



8. ERIOPHORUM. 



