a 
475 
+ + + + Bristles 6, scabrous upwards: achene smooth. 
11. R. filifolia Torr. Stems 3 to 6 dm. high, filiform, erect: leaves setaceous: 
corymbs 2 to 4, distant, capitate: spikelets lanceolate, brown, densely clustered : 
bristles rigid, nearly as long as the achene and tubercle: achene minute, obovate, 
lenticular, smooth and shining, twice as long as the compressed triangular-ovate 
ciliate tubercle.—South Atlantic and Gulf States to Texas. 
12. R. fuscoides Clarke. Stems 1.5 to4.5 dm. high, erect: leaves linear: corymbs 
capitate, in pairs at the summit of the stem, and often with a third rather distant 
lateral one: spikelets ovate, brown: bristles as long as the oval or orbicular, len- 
ticular, dark brown achene (rarely twice as long): tubercle white, conical, obtuse. 
(RK. fascicularis var, distans Chapm.)—Florida and Texas (Hall). 
13. R. gracilenta Gray. Stems (3 to 6 dm. high) and leaves filiform or setaceous: 
corymbs 2 or 3, distant, capitate, brown: spikelets densely clustered, ovate-lanceo- 
late: bristles twice as long as the oval dull achene, which is as long as the slender 
subulate tubercle.—From the south Atlantic and Gulf States to Texas. 
14. R. Grayii Kunth. Stem solitary, 6 to 9 dm. high, 3-angled: leaves linear, 
rigid, shining: corymbs 3 or 4, distant, capitate: spikelets few, large, ovate: 
bristles as long as the achene and tubercle: achene round-obovate, tumid, slightly 
pitted, dull; tubercle short-conical, dilated at base,—From the south Atlantic 
States to Texas. 
eee + + Bristles scabrous upwards: achene transversely rugose. 
15. R. cymosa Nutt. Stems 6 to 9 dm, high, 3-angled: leaves narrowly linear: 
corymbs mostly 3, distant, open or contracted; spikelets ovate, clustered, light 
brown: scales mucronate: achene broadly obovate, lenticular, faintly rngose, twice 
as long as the 8 to 6 bristles; tubercle broadly conical, compressed, a fourth as long 
as the achene.—From the Atlantic and Mississippi Valley States to Texas. 
16. R. rarifloraEll. Stems (3 to 4.5 dm, high) and leaves bristle form, the former 
commonly reclining: corymbs 2 or 3, remote, spreading: spikelets few and scattered, 
ovate, pedicelled: achene broadly obovate, lenticular, strongly rugose, twice as long 
as the 6 fragile bristles; tubercle flat, broadly conical, a third as long as the achene.— 
From the south Atlantic States to Texas. ; 
17. R. microcarpa Baldwin. Stems 6 dm. high, erect, slender, nearly terete: 
leaves narrowly linear: corymbs 4 to 6, slender, spreading, compound: spikelets 
small, round-ovate, scattered: bristles 5 or 6, as long as the round-obovate len- 
ticular strongly rugose achene, which is tipped with a very short and broad tuber- 
cle.—From the south Atlantic States to Texas. 
18. R. caduca Ell. Stems stout, 9 to 12 dm. high, 3-angled: leaves broadly 
linear: corymbs 4 to 6, compound, remote, the branches and short pedicels erect: 
spikelets very numerous, approximate, ovate: scales caducous: bristles 6, slender, 
twice as long as the obovate lenticular faintly rugose achene (4 to8 on the spikelet) : 
tubercle flat, conical, ciliate, half as long as the achene,—From the south Atlantic 
States to Texas. 
19. R. schcenoides Britton. Stems 6 to 9 dm. high, 3-angled: leaves linear: 
corymbs 3 to 5, compound, the lower ones remote: spikelets small, ovate, crowded: 
bristles 6, strongly hispid, as long as the achene and tubercle: achene obovate, tlat- 
tened, strongly rugose; tubercle broadly conical, flat, a fourth as long as the achene. 
(R. Elliottii Dietr. R. multiflora Gray.)—South Atlantic States to Texas (near Sabine 
Pass). 
20. R. patula Gray. Stems 6 to9dm. high, 3-angled, slender above: leaves linear: 
corymbs 3 to 5, remote, compound, widely spreading: spikelets scattered, ovate, on 
slender stalks: bristles 6, rather longer than the round-obovate lenticular achene: 
tubercle flat, conical, ciliate on the edges, half as long as the achene.—South 
Atlantic States to Texas. 
