CYPERACEAE 187 



Style-branches or stigmas 2 : achenes lenticular. 



Spikelets peduncled, forming umbels, or solitary and sessile. 

 Perennial : leaf-blades strongly involute. 



Bracts of the involucre shorter than the spikelets. 1. F. schoenoides. 



Bracts of the involucre or some of them longer than the spikelets. 

 Base of the style swollen. 



Scales coriaceous, shining. 2. F. spadicea. 



Scales thinner, dull. 3. F. castanea. 



Base of the style not swollen. 4. F. Drummondii. 



Annual : leaf-blades flat or nearly so. 5. F. laxa. 



Spikelets several, sessile, forming a terminal head. 



Scales acuminate : achenes obovoid. 6. F. Vahlii. 



Scales subulate-tipped : achenes oblong-cylindric. 7. F. perpusilla. 



Style-branches or stigmas 3 : achenes 3-angled. 



Spikelets narrow, or if relatively thick, in simple'umbels. 



Umbel mostly simple: spikelets ovoid or oval, blunt: achenes distinctly 



reticulated. 8. F. Frankii. 



Umbel mostly compound : spikelets linear-oblong, acute : achenes smooth or 



indistinctly reticulated. 9. F. autumnalis. 



Spikelets globular or about as thick as long, in decompound umbels. 10. F. miliacea. 



1. Fimbristylis schoenoides Vahl. Perennial, glabrous. Leaves erect or nearly 

 so : blades attenuate from the slightly dilated bsaes, involute : scapes more or less densely 

 tufted, 1-4 dm. tall, mostly overtopping the leaves, smooth : bracts of the involucre shorter 

 than the spikelets, inconspicuous : spikelets solitary, or 2 or 3 together forming an umbel, 

 and the earliest one sessile, ovoid or conic-ovoid, 5-12 mm. long, 3-4 mm. thick, pale 

 brown : scales rather blunt, firm : stigmas 2 : achenes lenticular, broadly obovoid, barely 

 1.5 mm. long, lustrous, whitish, not pointed. 



In low grounds, Florida. Also in tropical Asia. 



2. Fimbristylis spadicea (L. ) Vahl. Perennial by a thickened base, glabrous. 

 Leaves few : blades about 2 mm. wide when unrolled, their sheaths dark brown : scapes 

 stiffj slender, 3-angled, wiry, tall, usually longer than the strongly involute, rigid leaves : 

 bracts of the involucre 3-6, erect : umbel several-rayed, the rays nearly erect, 5-15 cm. 

 long : central spikelets of the umbels and umbellets sessile, the others pedicelled : spikelets 

 ovoid or ovoid-cylindric, acute, 5-12 mm. long, about 2 mm. in diameter : scales oval, 

 obovate, or orbicular, obtuse or subacute, coriaceous, glabrous, shining, dark brown with 

 green midribs: stigmas 2: achenes lenticular, obovoid, 1.5 mm. long, brown. 



In marshes and shallow water, Virginia to Florida, near the coast. Widely distributed in tropical 

 America. 



3. Fimbristylis castanea (Michx.) Vahl. Perennial by a thick base. Leaves few ; 

 blades involute, less than 2 mm. wide, their sheaths green and more or less pubescent : 

 scapes slender, 3-angled, 2-5 dm. tall, usually exceeding the leaves : bracts of the invo- 

 lucre 2-4, short : umbel simple or compound, the rays 1-5 cm. long : the central spike- 

 lets sessile : spikelets oblong, 6-10 mm. long, 2-3 mm. in diameter : scales thin, brown 

 with lighter midveins, broadly oblong or nearly orbicular, dull, puberulent, obtuse or 

 mucronate : stigmas 2: achenes obovoid or oblong, about 1.5 mm. long, biconvex, pale 

 brown, that of the prairie plant is shorter and less tapering to the base. 



On salt meadows, southern New York to Florida and Louisiana. Also in wet soil in the interior 

 from Ontario, Michigan and Illinois to Kansas and Texas, and in tropical America. A variety with 

 copiously pubescent leaves and scapes, is F. castanea puberula, (Michx. ) Britton. It ranges from Georgia 

 and Florida to Texas. 



4. Fimbristylis Drummondii (Torr. & Hook.) Britton. Perennial, glabrous. 

 Leaves rather stiff ; blades attenuate from the slightly dilated base, convex beneath, 

 scarcely 2 mm. wide : scapes erect, somewhat tufted, about 9 dm. tall, twice as long as the 

 leaves, smooth, deeply channeled on one side : bracts of the involucre 2-3, shorter than 

 the inflorescence : umbel compound, with 4-6 curved rays 2-5 cm. long : spikelets oblong- 

 ovate, about 12 mm. long, 3-5 mm. broad, pale brown, acute : scales mucronulate, rigid, 

 slightly keeled near the apex : style not thickened at the base : stigmas 2 : achenes lenticular, 

 obovoid, about 1.5 mm. long, apiculate at the apex. [Isolepis Drummondii Torr. & Hook.] 



In low grounds, Texas. 



5. Fimbristylis laxa Vahl. Annual, glabrous or sparingly ciliate. Leaves pale 

 green ; blades flat, about 1 mm. wide : scapes slender, flattened, striate, densely tufted, 

 erect or ascending, 5-40 cm. long, usually longer than the leaves : bracts of the involucre 

 3-5 : umbel simple or slightly compound, the central spikelets sessile : spikelets ovoid or 

 ovoid-oblong, 6-12 mm. long, about 2 mm. in diameter : scales ovate, thin, pale greenish 

 brown, subacute or mucronulate : stigmas 2 : achenes biconvex, obovoid, fully 1 mm. long, 

 brown, longitudinally ribbed, the ribs tubercled and connected by very fine cross lines. 



In moist soil, southern Pennsylvania to Missouri, Florida and Texas. Also in tropical America. 



6. Fimbristylis Vahlii (Lam. ) Link. Annual. Leaves setaceous or almost filiform, 

 rough : scapes very slender, densely tufted, compressed, striate, 2-10 cm. high, longer than 

 or equalling the leaves : bracts of the involucre 3-5, erect, much exceeding the simple 



