250 CYPERACEAE. 



5. Eleocharis olivacea Torr. Bright green Spike-rush. (Fig. 581.) 



Eleocharis olivacea Torr. Ann. Lye. N. Y. 3: 300. 1836. 



Perennial by running rootstocks, often tufted and 

 matted, culms very slender, bright green, erect or re- 

 clining, flattened, i'-4/ long. Upper sheath with a 

 white hyaline limb; spikelet ovoid, acute or obtuse, 

 much thicker than the culm, several -many-flowered, 

 about 2 // long, i" in diameter; scales ovate, thin, 

 acute, reddish-brown, with a green midvein and nar- 

 row, scarious margins; stamens 3; style 2-cleft; bris- 

 tles 6-8, slender, retrorsely barbed, longer than the 

 achene and tubercle; achene obovoid, similar to that 

 of the preceding species but twice as large, 3-4 times 

 the length of the conic acute tubercle. 



In wet soil, Maine to southern Ontario and Pennsylva- 

 nia, south to South Carolina, mostly near the coast. 

 Aug. -Sept. 



6. Eleocharis atropurpurea (Retz) Kunth. Purple Spike-rush. (Fig. 582.) 



Scirpus atropurpureus Retz, Obs. 5: 14. 1789. 

 Eleocharis atropurpurea Kunth, Enum. 2: 151. 



1837- 



Annual, roots fibrous, culms tufted, very slender, 

 i / ~3X / high. Upper sheath i-toothed; spikelet ovoid, 

 many-flowered, subacute, i>^ // -2 // long, i" in diam- 

 eter or less; scales minute, ovate-oblong, obtuse or 

 the upper acute, persistent, purple-brown with green 

 midvein and very narrow scarious margins; stamens 

 2 or 3; style 2~3-cleft; bristles 2-4, fragile, white, 

 minutely downwardly hispid, about as long as the 

 achene; achene jet black, shining, %" long, smooth, 

 lenticular; tubercle conic, minute, depressed but 

 rather acute, constricted at the base. 



In moist soil, Nebraska and eastern Colorado to Central 

 America, east to Florida; widely distributed in tropical 

 America. July-Sept 



7. Eleocharis capitata (I,.) R. Br. Capitate Spike-rush. (Fig. 583.) 



Scirpus capiiatus I,. Sp. PI. 48. 1753. 



Eleocharis capitata R. Br. Prodr. Fl. Nov. Holl. i: 225. 

 1810. 



Annual, roots fibrous, culms densely tufted, nearly 

 terete, almost filiform, rather stiff, 2 / -io / tall. Upper 

 sheath i-toothed; spikelet ovoid, obtuse, much thicker 

 than the culm, i>^ // -2^ // long, i // -i>^ // thick, many- 

 flowered; scales broadly ovate, obtuse, firm, pale or 

 dark brown with a greenish midvein, narrowly scari- 

 ous-margined, persistent; stamens mostly 2; style 2- 

 cleft; bristles 5-8, slender, downwardly hispid, as 

 long as the achene; achene obovate, jet black, 

 smooth, shining, nearly y^' long; tubercle depressed, 

 apiculate, constricted at the base, very much shorter 

 than the achene. 



In moist soil, Maryland to Florida, west to Indiana and 

 Texas. Widely distributed in tropical regions. July-Sept. 



