540 
nearly twice as long as the palet. (Tricuspis mutica Torr.)—Dry hills, western 
Texas to Arizona and northern Mexico. 
+ + Second empty glume 8 to 5-nerved. 
14. S. trinerviglumis (Munro) Kuntze. Culms 4 to 8 dm. high, tufted, leafy: 
leaves 2 to 3 dm. long: panicle 1 to 2dm. long; branches appressed, about equaling 
the intervals: spikelets 7 to 10 mm, long, 6 to 8-flowered; empty glumes about 
equaling the lower florets; floral glume subeutire or emarginate, often mucronate, 
pubescent below the middle, one-third longer than the ciliate palet. (Tricuspis 
trinerviglumis Munro.)—Western Texas to Colorado and Arizona. 
15. S. Buckleyana (Vasey.) Culms slender, about 5 dm. high: leaves narrow, 
subinvolute, pungent-pointed: panicle 1.5 to 2.5 dm. long; branches erect, 2 to 4 
cm. long, slightly exceeding the intervals: spikelets 4 to 6 mm. long, 3 to 5-flow- 
ered; second empty glume larger than the first and about equaling the florets; 
floral glume ovate-oblong, slightly 2-lobed at the obtuse apex, pubescent on the 
nerves below the middle; palet one-fourth shorter than the glume. (Triodia Buck- 
leyana Vasey.)—Rare, southern Texas. 
sees * * Diacious: panicles linear: staminate spikelets compressed; pistillate spike- 
. lets fusiform, 
16. S. Wrightii Vasey. Both sexes stoloniferous and very leafy: staminate plant, 
culms 1 to 3 dm. high; spikelets nearly 1 em. long, in short, few-flowered panicles 
(Poa Texana Vasey): pistillate, culms 3 to 6 dm. high; panicle 1 to 2 dm. long; 
spikelets 8 to 14 mm. long, 4 to 8-flowered; empty glumes slightly shorter than the 
lower florets, 3 (or indistinctly 5)-nerved; floral glume ovate, entire or slightly 
mucronate, smooth, prominently 3 to 5-nerved, subcoriaceous with broad mem- 
branaceous margins; palet rigid, slightly ciliate, one-third shorter than the 
glume.—Presidio County, Texas. An anomalous species, very unlike the other spe- 
cies of the genus, but fitting here better than in any other established genus, 
59. DIPLACHNE Beauv. 
Spikelets 2 to 12-flowered, linear, compressed or subterete, sessile or 
short pedicelled on the lower sides of the rays of the racemose panicle 
(rarely in a simple spicate panicle), rays horizontal to nearly erect, 
spikelet-bearing to the base: empty glumes 1-nerved, acute or some- 
what tridentate, the second larger but not exceeding the adjacent 
floret; floral glumes membranaceous, rarely rigid, obtuse, truncate or 
acute, sometimes short-awned or 3-toothed, often pubescent on the 3 
nerves near the base, slightly exceeding the palet: grain translucent 
amber colored, oblong or subterete: internode of rachilla glabrous. 
—Perennial grasses with abundant narrow leaves; some of the species 
widely diffused but none of them common. 
* Panicle simple, linear. 
1. D. spicata Doell. Culms slender, 1 to 2 dm. high, nearly naked above the base: 
leaves at the base numerous, narrow, involute, 3 to 5 cm. long: panicle 5 to 10 em. 
long: spikelets about 6 mm long, 8 to 10-flowered; second empty glume obtuse or 
somewhat toothed, one-third longer than the acute first glume; floral glume ovate, 
short-awned between the obtuse lobes, pubescent at the base rachilla pubescent at 
the nodes. (D, Reverchoni Vasey.)—Among rocks, Llano County, central Texas, 
“ * Panicle racemose, more or less spreading, 
+ Floral glume truncate or obtusely lobed. 
