574 FLORA OF TEXAS. 



pointed, grayish and minutely pitted; culms filiform, 

 3-angled, 6-12' high ; leaves and elongated involucre very 

 narrow. Margins of ponds and streams. Red River. July- 

 September. Rays 1-2' long; spikelets 4"-7" long.— 

 Marcy, 



% 2. Ctpebus proper. Style Z-cleft ; nut 3-angled ; joints oftherachis winged hy the 

 adnate decurrent scales, rarely wingless. 



Spicaxt. Umbel simple or compound; spikelets few-many-flowered, distinct, spreading, 

 forming loose or compact spikes at the summit of the rays; scales rigid, 7-11- 

 nerved ; joints of the rachis commonly conspicuously winged ; stamens 3. 



* Spikelets approximate or crowded on all sides of the common rachis, forming oblong or 

 cylindrical spikes. 



C. STRIGOSUS, L. Umbel large, 4-8-rayed, simple or com- 

 pound, much shorter than the involucre ; involucels bristly, 

 shorter than the dense oblong spikes ; spikelets yellowish, 

 linear, acute, compressed, 6-10-flowered ; scales somewhat 

 scattered on the very slender rachis, oblong-lanceolate, 

 acute, closely appressed, much longer than the linear-ob- 

 long acute minutely dotted diuW nut; culms (l°-3° high) 

 tumid at the base, as long as the broadly linear leaves. 

 Swamps and damp soil. July-September. Rays 4-6' 

 long; spikelets i'-f long; slieatli of the rays bristle- 

 pointed. Wichita Mountains. 



C. ScHWEiNiTZii, Torr. Culm 8-12' high, triquetrous, 

 rough on the angles ; leaves shorter than the stem, about a 

 line wide; umhel simple, erect, 4-6-rayed; rays elongated, 

 unequal ; sheaths truncate, entire ; involucre 3-5-leaved, 

 longer than the leaves, scabrous on the margin ; spikelets 

 6-7, alternate, approximate, in cylindric clusters, 6-8-flow- 

 ered, with a small, setaceous bract at the base of each ; 

 scales membranaceous on the margin; stamens 3; style 

 3-cleft, scarcely longer than the smooth achenia. Northern 

 Texas. 



C. MiCHAUXiAJTUS, Schultes. Umhel compound, 4-6- 

 rayed ; rays short with the sheaths pointed ; spikes loose, 

 mostly shorter than the leafy involucels ; spikelets spread- 



