C1PERACEAE. 57 



1. Schoenus nlgricans L. Sp. PI. 43. 1753. 



Glabrous; culms 2-7 dm. tall, mostly longer than the leaves. Leaves 

 similar to the culm, stiff, sharp-pointed, semiterete, 0.5-1.5 mm. thick, their 

 bases dark brown or nearly black, shining; involucre of 2 bracts, one of them 

 elongated, sometimes 8 cm. long; spikelets about 1 em. long in a dense, ter- 

 minal, capitate cluster, 5-8-flowered, compressed, their scales dark chestnut- 

 brown, or nearly black, lanceolate, carinate, acuminate, somewhat shining; 

 perianth-bristles 6, plumose; achene ellipsoid, white, shining, about 2 mm. long; 

 shorter than the bristles. 



Swamps, Andros, New Providence, Eleuthera, Crooked Island, Caicos : Flor- 

 ida ; Cuba ; southern California ; Europe. BLACK-HEADED SEDGE. 



11. SCLKRIA Berg. Vet. Acad. Handl. 26: 142, 1765. 



Leafy sedges, mostly perennial, the spikelets small, clustered in terminal, 

 or terminal and axillary fascicles, or sometimes interruptedly spicate. Flowers 

 monoecious. Fertile spikelets 1-flowered. Staminate spikelets many-flow T ered. 

 Scales imbricated, the 1-3 lower and sometimes also the upper ones of the fertile 

 spikelets empty. Perianth none. Style 3-cleft, slender or sometimes swollen 

 at the base, deciduous. Ovary supported on a disk (hypogynium), or this 

 wanting. Stamens 1-3. Achene globose or ovoid, obtuse, crustaceous or bony, 

 white in our species. [Greek, in allusion to the hard fruit.] About 200 

 species, natives of tropical and temperate regions. Type species: Scleria 

 Flagellum-nigrorum Berg. 



Annual ; achene with sharp transverse ridges. 1. S. verticillata. 



Perennial ; achene smooth. 2. . lithosperma. 



1. Scleria verticillata Willd. Sp. PI. 4: 317. 1805. 



Roots fibrous; culms very slender or filiform, 3-angled, smooth or nearly 

 so, erect, 1-5 dm. tall. Leaves very narrowly linear, 0.5-1 mm. wide, erect, 

 shorter than the culm; spikelets in several separated clusters; bracts bristle- 

 like; scales glabrous; achene globose, 1 mm. in diameter, crustaceous, marked 

 by sharp distinct tranverse ridges, or somewhat reticulated; hypogynium none. 



Borders of marshes. New Providence : eastern United States ; Cuba. Low 

 NUT-RUSK. 



2. Scleria lithosperma (L.) Sw. Prodr. 18. 1788. 



Scirpus lithospermus L. Sp. PI. 51. 1753. 

 Scleria filiformis Sw. Prodr. 19. 1788. 



Perennial by rather short rootstocks, the culms often clustered, slender, 

 weak, glabrous, 2-6 dm. long. Leaves 0.5-3 mm. wide, the upper elongated, 

 the lowest reduced to pubescent or puberulent sheaths; panicles 1-3, distant, 

 glabrous, small, stalked or the upper sessile; bracts filiform, glabrous; achene 

 obovoid-ellipsoid, white, smooth, shining, about 2 mm. long, its base trigonous; 

 hypogynium none. 



Coppices and scrub-lands, Abaco, Great Bahama. Berry Islands and Andros 

 to Mariguana and Inagua : Florida ; West Indies ; continental tropical America ; 

 Old World tropics. SLENDER NUT-RUSH. 



