186 CYPERACEAE 
32. Eleocharis tricostata Torr. Perennial by short rootstocks. Scapes very slender, 
erect, compressed, striate, 3-6 dm. tall: upper sheath obliquely truncate, toothed on one 
side: spikelet oblong, becoming oblong-cylindric, obtuse, many-flowered, 10-18 mm. long, 
2-3 mm. in diameter : scales ovate, thin, deciduous, obtuse, brown with green midveins and 
scarious margins: perianth-bristles none: stigmas 3: achenes obovoid, 0.8-1 mm. long, 
3-angled, brown, dull, papillose, with the three angles strongly ribbed ; tubercle conic, 
acute, light brown, constricted at the base, minute, very much shorter than the achene. 
In wet soil, southern New York to Florida. Summer and fall. 
33. Eleocharis ténuis (Willd.) Schult. Perennial by rootstocks. Scapes tufted, 
filiform, mostly erect, 4-angled with concave sides, 2-4 dm. tall: upper sheath obliquely 
truncate, toothed an one side: spikelet narrowly oblong, mostly acute, many-flowered, 
thicker than the scape, 6-10 mm. long, about 2 mm. in diameter: involucral bract 1: 
scales thin, obovate or ovate-oblong, obtuse, the midvein greenish, the margins scarious : 
perianth-bristles 2-4, shorter than the achene, fugacious or wanting: stigmas 3: achenes 
obovoid, about 1 mm. long, obtusely 3-angled, yellow to brown, irregularly ridged-reticu- 
lated or papillose, more or less persistent on the rachis of the spikelet after the scales have 
fallen ; tubercle conic, short, acute. 
In wet soil, Cape Breton Island to Ontario, Manitoba, Florida and Texas. Spring and summer. 
34. Eleocharis arenícola Torr. Perennial by horizontal rootstocks. Scapes very 
slender, tufted, 1.5—4-5 dm. tall, grooved, mostly erect: spikelets oblong to ovoid-oblong, 
4-12 mm. long, 2.5-3.5 mm. thick, many-flowered : scales oblong or ovate, thin, blunt, 
each with a brown apex and whitish margins: perianth-bristles 6, persistent, the longer as 
long as the achene: achenes 3-angled, about 1 mm. long, oblong-obovoid or obovoid, faintly 
reticulated ; tubercle thick, deltoid. 
On sandy shores and in swamps, South Carolina to Florida and Texas. Spring to fall. 
35. Eleocharis acuminata (Muhl.) Nees. Perennial by stout rootstocks, similar to 
the next preceding species but stouter. Scapes flattened, striate, slender but rather stiff, 
tufted, 2-5 dm. tall: upper sheath truncate, sometimes slightly 1-toothed : spikelet ovoid 
or oblong, obtuse, thicker than the scape, many-flowered, 6-12 mm. long: scales oblong or 
ovate-lanceolate, acute, purple-brown with greenish midveins and hyaline white margins, 
deciduous: perianth-bristles 1—5, shorter than or equalling the achene, fugacious, or want- 
ing: stigmas 3, exserted: achenes obovoid, 1.5 mm. long, obtusely 3-angled, light vel- 
lowish brown, papillose, much longer than the depressed conic acute tubercle, persistent 
on the rachis as in £F. tenuis. 
In wet soil, Anticosti to Manitoba, Georgia, Louisiana and Nebraska. Summer. 
36. Eleocharis cylindrica Buckl. Perennial by slender rootstocks. Scapes very 
slender, tufted: spikelets linear-cylindric, or slightly flattened, 1-2 cm. long, about 3 mm. 
thick, acutish, many-flowered : scales various, the lower ovate and blunt, the upper ovate 
or oblong-lanceolate and acute, with whitish hyaline margins: perianth-bristles wanting : 
achenes obovoid, fully 0.5 mm. long, yellowish, constricted at the ends but especially under 
the acute tubercle. 
In sandy soil, Texas. Summer and fall. 
37. Eleocharis rostellàta Torr. Perennial by a short caudex. Scapes slender, wiry, 
the fertile ones erect or ascending, the sterile reclining aud rooting at the summit, grooved, 
3-15 dm. long: upper sheath truncate: spikelet oblong, narrowed at both ends, thicker 
than the scape, 10-20-flowered, 6-12 mm. long, about 2 mm. in diameter : scales ovate, 
obtuse or the upper acute, green with somewhat darker midveins: perianth-bristles 4-8, 
retrorsely barbed, longer than the achene and tubercle: stigmas 3: achenes oblong-ob- 
ovoid, 1.5 mm. long, obtusely 3-angled, their surface finely reticulated ; tubercle conic- 
subulate, about 4 as long as the achene or shorter, capping its summit, partly or entirely 
falling away at maturity. 
In marshes and wet meadows, New Hampshire to Vermont and western New York, British Colum- 
bia, Florida, Texas, Mexico and California. Also in Cuba. Summer and fall. 
11. FIMBRISTYLIS Vahl. 
Annual or perennial scapose herbs. Spikelets umbellate or capitate, terete, several to 
many-flowered, subtended by a 1-many-leaved involucre, their scales spirally imbricated 
all around, mostly deciduous, allfertile. Perianth none. Stamens 1-3. Style pubescent 
or glabrous, its base usually much enlarged, but falling away from the summit of the 
achene at maturity. Stigmas 2-3. Achenes lenticular, biconvex, or 3-angled, reticulated, 
cancellate, or longitudinally ribbed or striate. The plants flower mainly in summer and fall. 
