FLORA OF THE DISTRICT OF COLUMBIA. 95 



2. KX"LLINGA Rottb. 



1. Kyllinga pumila Michx. 

 Holmead Swamp (Waite). Coastal Plain. 



3. DULICHIUM L. Rich. 



1. Dulichium anmdinaceum (L.) Brit ton. 



In sluggish water bordering streams and ponds; frequent, especially along the 

 Potomac. July-Oct. Throughout the U. S. (D. sfathaceum Pers.) 



4. ELEOCHARIS R. Br. Spike rush. 



Spikelets not thicker than the spongy 4-angled culm. An aquatic, about 1 meter tall. 



10. E. quadrangulata. 

 Spikelets much thicker than the culm. 



Achenes 3-angled; stigmas 3. 



Culms capillary, 3-12 cm. tall (elongate when submerged) 1. E. acicularis. 



Culms slender but not capillary. 

 Plants perennial, with running rootstocks. 



Culms 4-aiigled, very slender; scales reddish chestnut 2. E. capitata. 



Culms flattened; scales fuscous 3. E. acuminata. 



Plants annual, tufted, without rootstocks. Achene reticulate, its tubercle 



nearly as large as the body 4. E. tuberculosa. 



Achenes biconvex; stigmas 2. 

 Plants rarely over 10 cm. tall, annual; upper sheaths with loose pale scarious tips. 



Spikelets dark, the scales purple-brown, with green midribs 5. E. olivacea. 



Spikelets pale, the scales whitish 6. E. flaccida. 



Plants mostly more than 20 cm. tall (10-20 in E. engeltnanni); upper sheaths with 

 close firm dark-margined tips. 



Plants perennial, with creeping rootstocks 9. E. palustris. 



Plants annual, densely tufted. 

 Spikelets cylindric, tapering at the apex, commonly 1 cm. long; bristles 



about equaling the achene 7. E. eugelmauni. 



Spikelets ovoid or ovoid-oblong, blunt, rarely over 8 mm. long; bristles 

 exceeding the achene 8. E. obtusa. 



1. Eleocharis acicularis (L.) Roem. & Schult. 



Mud flats and shallow water along Piney Branch and the Potomac at Chain Bridge. 

 July-Sept. Throughout the U. S. 



Plants perennial by delicate capillary rootstocks. 



2. Eleocharis capitata (L.) R. Br. 



Moist open ground; Takoma Park and eastward; infrequent. Eastern U. S. {E. 

 tenuis Schult.) 



This species was originally described from Virginia as Scirpus capitatus. The culm 

 is described as terete and the spike as subglobose, but Dr. Blake, who has examined 

 the specimen in the British Museum, finds these statements to be erroneous, the plant 

 being the one with 4-angled culms and narrowly ovoid spikelets later named E. tenuis.^ 



3. Eleocharis acuminata (Muhl.) Nees. 



Moist open ground along the Potomac; frequent. May-June. Eastern states, north 

 to N. Y. {E. compressa Sulliv.) 



4. Eleocharis tuberculosa (Michx.) Roem. & Schult. 



Sandy bogs; vicinity of Brightwood; Holmead Swamp; Howard University 

 reservoir. July-Sept. Atlantic states. 



1 See Blake, S. F., Notes on the Clayton Herbarium. Rhodora 20: 23. 1918. 



