491 
or purple stigmas, an inch long, exserted: at maturity the rachis disar- 
ticdating readily at the oblique joints between the pistillate spikelets. 
1. T. dactyloides L. (GAMA Grass.) Culms tufted, 1 to 2m. high, stout: leaves 
coarse, 3 to6em. long, 2 to3dm. wide, flat, attenuate, usually somewhat hispid: spikes 
2 to 4 together at the apex and sometimes 1 or 2 lateral ones, 1 to 2 dm, long, rigid, 
the lower one-fourth pistillate: staminate spikelets 6 to 9mm. long, exceeding the 
internodes, often purple; pistillate spikelets 6 to 8 mm. long, about equaling the 
eylindrical joints in which they are embedded.—Low land, eastern Texas and east- 
ward, Var. MONOSTACHYA Vasey, of the same range, is smaller, 3 to 8 dm. high: 
cauline leaves 1 to 2 dm, long and 1 to 2em. wide, often glaucous: spike single and 
terminal: spikelets like those of the species. 
2. T. Floridanum Porter. Culms slender, 8 to 10dm, high, from strong horizontal 
rootstocks: leaves narrow, lem, wide or less, rigid, conduplicate or involute, usually 
smooth, 6dm. long: spike single, terminal, erect, rather slender, 1.5 to 2.5dim. long: 
staminate spikelets 2-ranked, secund, much exceeding the short internodes of the 
flat-backed rachis; pistillate portion usually less than one-fourth the length of the 
' spike.—Near the mouth of the Rio Grande. 
2. ELIONURUS HBK. 
Spike cylindrical, single and terminal, or lateral: spikelets two at 
each node, exceeding the shallow cavities in the white hairy rachis, one 
sessile and perfect, the other pedicelled and staminate: glumes 4; the 
lower one usually largest and thickest, keeled near the margins; the 
second smaller and thinner; third and fourth hyaline: stamens 3: 
styles distinct; stigmas plumose, slightly exserted. 
1. BE. tripsacoides HBK. Culms 1 to 1.5 m, high, stout, erect, smooth or 
slightly pubescent near the nodes: leaves slender, involute, smooth, 2 to 3 dm. long: 
spikes terminal and lateral, 1 to 1.5 dm. long, on long peduncles; rachis and pedi- 
cels of staminate florets white ciliate: outer glumes hispid-ciliate near the margins, 
otherwise smooth.—Throughout Texas and eastward to Florida. 
2, EB. barbiculmis Hack. Culms 6 to 9 din. high, densely pubescent at the nodes 
and somewhat velvety below: radical leaves numerous, almost capillary, involute, 
curved, thinly pubescent with long white hairs near the base: spikes mostly ter- 
minal, about 1 dm, long; rachis, pedicels, and first and second glumes white villous,— 
Table-lands, western Texas. 
3. ROTTBGILLIA L. f. 
Spikes single, terminal or terminal and lateral, cylindrical or slightly 
compressed: spikelets in pairs on alternate sides at each node of the 
thickened rachis; one perfect, sessile, imbedded in a cavity; the other 
neutral, staminate or sometimes perfect on a thickened pedicel the length 
of the cavity: outer empty glumes coriaceous or thickened: inflores- 
cence usually glabrous throughout. 
* Joints of rachis readily disarticulating. 
1. R. cylindrica Chapm. Culms slender, erect, usually simple, terete, 3 to 6 dm. 
high: leaves mostly flat, thin, 2mm. wide, 2 to 3 dm. long: spikes mostly terminal, 
1 to 2 dm. long, 2 to 3 m'm. thick; rachis smooth: perfect spikelets 5 to 6 mm. long, 
equaling the nearly straight internode; outer glume obtuse, thickened, obscurely 
pitted: pedicellate spikelets rudimentary, small.—Throughout Texas. 
