1. Plants densely tufted; rhizomes absent; culms 1 mm. or less thick; blades 3-7 

 cm. long, 1 mm. broad basally, arcuate-filiform in the distal part; 

 bracts 2 (rarely 3), the longer ones 17-37 mm. long, filiform most 

 of the length 3. D. nivea. 



1. Plants with extensively creeping orangish or whitish rhizomes; culms 1.5-3 



mm. thick basally; blades 6-25 cm. long, 1.2-4 mm. broad basally 

 and at least 1 mm. broad even in the distal part; bracts several, the 

 longer ones (20-) 40-130 mm. long, not filiform except perhaps 

 at the extreme apex (2) 

 2(1). The white spot at the base of the longer bracts 5-20 (-25) mm. long, a 

 (third to a) fifth to a tenth as long as the bracts; bracts 3 to 6 

 (or 7) 1. D. colorata. 



2. The white spot at the base of the longer bracts 25-50 mm. long, about half as 



long as the bracts; bracts 6 to 10 2. D. latifolia. 



1. Dichromena colorata (L.) Hitchc. White-topped umbrella grass. Figs. 241 



and 242. 



Rhizomes usually orangish, 2-3 mm. thick, extensively creeping, scaly; culms 

 12-56 cm. long, erect or often decumbent at the very base; leaves crowded basally, 

 mostly rather stiffly ascending, 2-6 mm. broad, linear-involute at the tip; bracts 

 3 to 6 (or 7), mostly basally ascending but for the most of the length spreading 

 or slightly reflexed, lanceolate, very unequal, the longer ones (3-) 5-15 cm. 

 long, (1.5-) 2.5-5 mm. broad basally, with a white spot 5-20 (-25) mm. long. 



Locally frequent in swales, ditches and wet places generally, s.e. Tex., Rio 

 Grande Plains and Edwards Plateau, rare in s. part of e. Tex., w. to Terrell Co. 

 in the Trans-Pecos, (spring-) summer widespread in Carib. region, n. to Va. and 

 the Gulf States; e. Mex. 



2. Dichromena latifolia Ell. Figs. 241 and 242. 



Perennial with rhizomes 2-3 mm. thick; culms rather stiffly erect the full 

 length, 4-8 (-10) dm. long, 2-4 mm. thick basally; leaves crowded basally, ascend- 

 ing, 4-6 mm. broad basally, tapered upward and involute in the distal third, 

 apically pointed; bracts 6 to 10 mostly basally ascending but for most of the 

 length spreading or slightly reflexed, lanceolate, very unequal, the longer ones 

 5-10 cm. long, 4-10 mm. broad in the lower half, with a white spot 25-50 mm. 

 long (about half as long as the bract) . 



Locally frequent in poorly drained pine savannahs, s.e. Tex (Hardin and 

 Jefferson cos. only), summer; Gulf States and n. to N.C. 



3. Dichromena nivea (Boeck.) Britt. Fig. 241. 



Densely tufted; rhizomes absent; culms weak, ascending, 1-3 (-4) dm. long, 

 about 1 mm. thick or less; leaves in the lower part, flaccid, 3-7 cm. long, about 

 1 mm. broad basally, arcuate-filiform; bracts 2 (rarely 3), weak, the longer ones 

 17-37 mm. long, filiform most of the length, with a white spot only at the very 

 base, D. Reverchonii S. H. Wright, Rhynchospora nivea Boeck. 



Locally frequent in creek beds through limestone on Tex. Edwards Plateau, 

 rare in n.-cen. Tex. and Okla. (Marshall Co.), summer; also Ark. 



13. Rhynchospora Vahl (corr. Willd.) Beak-rush 



Perennials (rarely annuals); culms leafy; inflorescence of each culm usually 

 divided into several discontinuous parts (branches of the culm), the largest part 

 (appearing terminal) usually subumbelliform (occasionally much-reduced) with 

 several unequal primary branches (each subtended by a bracteal leaf) and these in 

 turn bearing spikelets or glomerules or corymbs of spikelets; the several axillary 

 parts of the inflorescence below usually reduced as compared to the terminal part, 



467 



