250 CYPERACEAE. 
5. Eleocharis olivacea Torr. Bright green Spike-rush. (Fig. 581.) 
Eleocharis olivacea Torr. Ann. Lyc. N. Y. 3: 300. 1836. 
Perennial by running rootstocks, often tufted and 
matted, culms very slender, bright green, erect or re- 
clining, flattened, 1/-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, 1’’ 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, 
1/-314/ high. Upper sheath 1-toothed; spikelet ovoid, 
many-flowered, subacute, 114//-2’ long, 1/’ 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 (L.) R. Br. Capitate Spike-rush. (Fig. 583.) 
Scirpus capitatus I. Sp. Pl. 48. 1753. 
Eleocharis capitata R. Br, Prodr. Fl. Noy. Holl, 1: 225. 
1810. 
Annual, roots fibrous, culms densely tufted, nearly 
terete, almost filiform, rather stiff, 2’-10’ tall. Upper 
sheath 1-toothed; spikelet ovoid, obtuse, much thicker 
than the culm, 114’/-2%4”’ long, 1//-14”’ 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 14’ 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. 
