CYPERACEAE. 53 



2. Scirpus validus Vahl, Enum. 2: 268. 1806. 



Perennial by stout rootstocks; culms stout, smooth, terete, erect, l-'6 m. 

 tall, sheathed at the base. Involucre-bract 1, erect, shorter than the unil^el, ap- 

 pearing as if continuing the culm; umbel compound, its primary rays slender, 

 1-6 cm. long; spikelets several or many, oblong-conic, 1 to 5 together, 5-12 

 mm. long, 3-4 mm. thick; scales ovate, short-tipped; bristles 4-6, downwardly 

 barbed, as long as the achene or longer; stamens 3; style 2-cleft; acheue 

 obovate, plano-convex, mucronate. 



Ponds, Fortune Island : — Continental North America ; Bermuda ; Cuba ; Haiti ; 

 Porto Rico ; Jamaica. American Great Bulrush. 



7. DICHROMENA Michx. Fl. Bor. Am. 1:37. 1803. 



Leafy-stemmed sedges, perennial by rootstocks, the spikelets crowded in a 

 terminal head involucrate by the upper leaves, which are often white at the 

 base. Spikelets compressed, several-many-flowered. Scales spirally imbricated 

 all around, several of them with imperfect flowers, or empty. Perianth none. 

 Stamens 3. Style 2-cleft, its branches subulate. Achene lenticular, transversely 

 rugose, crowned with the broad persistent base of the style (tubercle). 

 [Greek, alluding to the two-colored involucral leaves.] About 8 species, na- 

 tives of America. Type species: Dichromena leiicocepliala Michx. 



Spikelets capitate: involucral bracts reflexed. 1. D. colorata. 



Spikelets subspicate ; bracts erect or the lower one spreading 2. D. inu(jucnsis. 



1. Dichromena colorata (L.) Hitchc. Eep. Mo. Bot. Gard. 4: 141. 1893. 



ScJioenus coloratus L. Sp. PI. 43. 1753. 



Dichromena leucocephala Michx. Fl. Bor, Am. 1: 37. 1803. 



Glabrous; culm slender, erect, rather sharply triangular, 0.3-0.6 m. tall. 

 Leaves distant, narrowly linear, about 2 mm. wide, much shorter than the 

 culm, those of the involucre 4-6, reflexed when mature, yellowish white at the 

 base; head globose, 1-2 cm. in diameter; spikelets narrowly oblong, acute; 

 scales membranous, lanceolate, nearly white, 1-nerved, subacute at the apex; 

 achene obovate, brown, nearly truncate at the summit, compressed, covered by 

 the tubercle which is not decurrent on its edges. 



Scrub-lands and borders of marshes, Abaco. Great Bahama, Andros and Ntnv 

 Providence to Caicos Islands and Inagua : — southeastern United States ; Bermuda : 

 Cuba to Porto Rico and Martinique ; Texas to Yucatan. Narrow-lEuVVed Dichro- 

 mena, White-headed Rush. 



2. Dichromena inagnensis Britton, spec, nov. 



Densely tufted; culm very slender, erect, about 3 dm. tall. Leaves 1-1.5 

 mm. wide, two-thirds as long as the culm ; involucral bracts 3-5, glabrous, 

 erect, green or whitened only at the base, or the lower one spreading and some- 

 times 14 cm. long; bractlets ciliolate; spikelets few, subspicate, nearly erect, 

 about 7 mm, long; scales white, obtusish; achene yellowish brown, a little 

 more than 1 mm, long, copiously transversely rugose, capped by a low flat- 

 conic tubercle of about one-fourth its length. 



Scrub-lands between Northwest Point and Southwest I^oint, Little Inagua (Xwih 

 and Taylor 125 if) . Endemic, Inagua Dichromena. 



8, RYNCHOSPORA Vahl, Enum. 2: 229. 1806. 



Leafy sedges, mostly perennial by rootstocks, with erect 3-angled or terete 

 culms, narrow flat or involute leaves, and ovoid oblong or fusiform, variously 



