182 CYPERACEAE 



branous, the lower sometimes bearing short blades : spikelet terete, cylindric, many-flowered, 

 rather acute, 2.5-4 cm. long, 4 mm. in diameter, not thicker than the scape : scales ovate, 

 orbicular or obovate, obtuse or the upper ones acute, narrowly scarious-margined, faintly 

 many-nerved, persistent : perianth-bristles 6, rigid, retrorsely barbed, as long as the body of 

 the achene, or shorter : stigmas 3, exserted : achenes obovoid, 1.5 mm. long, brown, shining, 

 with minute transverse ridges, convex on one side, very obtusely angled on the other, 2 or 

 3 times as long as the conic acute black broad-based tubercle. {_E. equisetoides ( Ell. ) Torr. ] 

 In water, Massachusetts to Michigan, Florida and Mexico. Also in the West Indies. Summer and 

 fall. 



2. Eleocharls cellulosa Torr. Perennial by horizontal rootstocks. Scapes obscurely 

 3-angled and invested by discolored sheaths at the base, terete above, 3-7 dm. tall, con- 

 tinuous : spikelet cylindric, 1.5-3 cm. long, 3-5 mm. thick : scales broadly obovate, with 

 white hyaline margins, appressed, rounded at the apex, minutely nerved : perianth-bristles 

 6, slightly unequal, nearly smooth : stigmas 3 : achenes broadly obovoid, copiously pitted, 

 1.5-2 mm. long excluding the tubercle, about as long as the bristles ; tubercle finally del- 

 toid, about ^ as broad as the widest part of the achene. 



In marshes near the coast, Florida to Texas. Also in the West Indies. Summer and fall. 



3. Eleocharis mutata ( L. ) R. & S. Perennial by stout rootstocks. Scapes sharply 

 4-angled, stout, not nodose, 6-12 dm. tall : sheaths purplish brown or green, sometimes 

 bearing short blades : spikelet terete, cylindric, 2-5 cm. long, 4 mm. in diameter, many- 

 flowered, about as thick as the scape : scales broadly ovate or obovate, obtuse or the upper 

 rather acute, scarious-margined, faintly many-nerved, persistent : perianth-bristles about 6, 

 rigid, retrorsely barbed, about as long as the achenes : stigmas 3 : achenes obovoid, 2.5 mm. 

 long, 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, southern Ontario to New Jersey, Michigan, Alabama, Missouri, 

 Texas and Guatem.ala. Also in the West Indies and South America. Summer and fall. 



4. Eleocharis Robbinsii Oakes. Perennial by slender rootstocks. Scapes slender, 

 3-angled, 1-6 dm. long, sometimes producing numerous filiform flaccid, sterile branches 

 from the base : sheaths appressed, obliquely-truncate ; spikelet subulate, few-flowered, not 

 thicker than the scape, 1-2 cm. long, 2 mm. in diameter : scales lanceolate or oblong- 

 lanceolate, strongly concave, faintly several-nerved, persistently clasping the rachis, nar- 

 rowly scarious-margined : stigmas 3 : perianth-bristles 7, equalling the achene and tubercle, 

 retrorsely barbed : achenes obovoid, 2 mm. long, light brown, deeply pitted, biconvex or 

 obtusely angled on the back, twice as long as the conic-subulate flattened tubercle, which 

 has a raised ring around the base. 



In shallow water. New Brunswick to Michigan and Florida. Summer and fall. 



5. Eleocharis elong^ta Chapm. Perennial from very slender rootstocks. Scapes 

 slender, tufted, chiefly submerged, 3-10 dm. long, terete, accompanied by phyllode-like 

 filiform sterile ones, "tender : spikelet cylindric, 1-2 cm. long, 2-2.5 mm. thick, 12-20- 

 flowered, acute : scales relatively distant, oblong-ovate, obtuse, prominently ribbed, with 

 a green back and brown margins : perianth-bristles 7, plumose : achenes obovoid, faintly 

 pitted, biconvex or slightly 3-angled, about 1 mm. long ; tubercle minute. 



In still water, Florida and Texas. Summer. 



6. Eleocharis ochre^ta (Nees) Steud. Perennial by slender rootstocks. Scapes 

 very slender, or filiform, pale-green, 3-angled, 0.5-2.5 dm. tall : upper sheath with a white, 

 hyaline, scarious limb : spikelet subacute, 2-3 times as thick as the scape, about 4 mm. 

 long, 2-3 mm. in diameter, several-flowered : scales pale green, oblong-lanceolate, obtuse 

 or the upper acute, hyaline, each with a faint midvein : perianth-bristles about 6, slender, 

 retrorsely barbed, somewhat longer than the achene : stigmas 2 : achenes 0.7-1 mm. long, 

 lenticular, obovoid, smooth, brown, 2-4 times as long as the conic acute tubercle. 



In wet soil, Virginia to Florida and Mississippi. Also in tropical America. Summer and fall. 



7. Eleocharis praticola Britton. Annual, relatively small. Scapes slender, 

 tufted, 6 cm. tall or less : spikelet ovoid or oblong-ovoid, about 2 mm. long : scales 

 brown, lanceolate or oblong-lanceolate, lax in age : perianth-bristles 5-7, retrorsely barbed, 

 shorter than the achene : stigmas 2 : achenes obovoid, about 0.5 mm. long, dark brown, 

 shining, the tubercle very small. 



In low places, Osceola County, Florida. Spring. 



8. Eleocharis oliv^cea Torr. Perennial by running rootstocks, often tufted and 

 matted. Scapes very slender, bright green, erect or reclining, flattened, 2-10 cm. long : 

 upper sheath with a white hyaline limb : spikelet ovoid, much thicker than the scape, 

 several-many-flowered, about 4 mm. long, 2 mm. in diameter : scales ovate, acute, reddish 

 brown, each with a green midvein and narrow scarious margins : perianth -bristles 6-8, 



