2. Eleocharis mutata (L,.) 
SEDGE FAMILY. 249 
R. & S. Quadrangular Spike-rush. (Fig. 578. ) 
Scirpus mutatus L,. Am. Acad. 5: 391. _ 1760. 
ag quadrangulatus Michx. Fl. Bor, Am. 1: 30. 
A 1803. 
Eleocharis quadrangulata R. & S. Syst. 2:155. 1817. 
Eleocharis mutata R. & S. Syst. 2: 155. 1817. 
Perennial by stout rootstocks, culms sharply 4- 
angled, stout, not nodose, papillose, 2°—4° tall. 
Sheaths purplish-brown or green, membranous, 
sometimes bearing short blades; spikelet terete, 
acute, cylindric, 1’-2’ long, 2’’ in diameter, many- 
flowered, about as thick as the culm; scales coria- 
ceous, broadly ovate or obovate, obtuse or the upper 
subacute, scarious-margined and sometimes with a 
narrow brown band within the margins, faintly 
many-nerved, persistent; bristles about 6, rigid, re- 
trorsely barbed, about as long as the achene; sta- 
mens 3; style 3-cleft; achene oboyoid, biconvex or 
slightly angled on the back, minutely cancellate, 
about twice as long as the conic acute tubercle, 
which is truncate or contracted at the base. 
In ponds, streams and swamps, northern New Jersey to Michigan, south to Alabama, Missouri, 
Texas and Guatemala. Also in the West Indies and South America. July—Sept. 
3. Eleocharis Robbinsii Oakes. Robbins’ 
Spike-rush. (Fig. 579.) 
Eleocharis Robbinsti Oakes, Hovey’s Mag. 7: 178. 1841. 
Perennial by slender rootstocks, culms slender, 3- 
angled, continuous, 6/-2° long, sometimes producing 
numerous filiform flaccid sterile branches from the base. 
Sheaths appressed, obliquely truncate; spikelet subulate, 
few-flowered, not thicker than the culm, 6/’/—10’ long, 
1// in diameter; scales lanceolate or oblong-lanceolate, 
obtuse or subacute, strongly concave, faintly several- 
nerved, persistently clasping the rachis, narrowly scari- 
ous-margined; style 3-cleft; bristles 6, equalling the 
achene and tubercle, retrorsely barbed; achene obovoid, 
light brown, biconvex or very obtusely angled on the 
back, somewhat longer than the conic-subulate flattened 
tubercle, which has a raised ring around its base. 
In shallow water, New Brunswick to Michigan, south to 
Florida, Aug.—Sept. 
4. Eleocharis ochreata (Nees) Steud. Pale Spike-rush. (Fig. 580.) 
falar ochreatus Nees in Mart. Fl. Bras. 2: Part 1, 
Meriofis ockreata Steud. Syn. Pl. Cyp. 79. 1855 
Perennial by very slender rootstocks, culms very 
slender, or filiform, erect, pale green, 3-angled, 2/—10’ 
tall. Upper sheath with a white, hyaline, scarious 
limb; spikelet oblong or ovoid, subacute, 2-3 times as 
thick as the culm, about 2’ long, 1%// in diameter, 
several-flowered; scales pale green, oblong-lanceolate, 
obtuse or the upper acute, thin, hyaline with a faint 
midvein; style 2-cleft; bristles about 6, slender, re- 
trorsely barbed, somewhat longer than the achene; 
achene 4’ long, lenticular, obovate, smooth, brown, 
2-4 times as long as the conic acute tubercle, which 
is often constricted at the base. 
In wet soil, southern Virginia to Florida and Missis- 
sippi. Also in Wyoming and Montana and in tropical 
America. Aug.—Sept. 
