No. 29. 
CHLORIS ALBA Presl. 
Plant annual. 
Root slender, numerous. 
Culms branching from the base and lower axils, procumbent at the base, rarely 
rooting at the lower nodes, glabrous, commonly 14 to 3 feet high, often less. . 
Leaves 4 to 8 on the stem; sheaths glabrous, more or less bladdery-inflated, 
often loose, usually not contiguous; blades 1 to 24 lines broad, 9 inches long or 
much shorter, flat, glabrous beneath, scabrous on the margins and above. 
Inflorescence a sheathed or pedunculate cluster of sessile spikes. Spikes 5 to 
15, 2 to 34 inches long, only slightly spreading; rachis filiform, terete, straight, 
scabrous; spikelets closely set, sessile, in 2 rows along one side. 
Spikelets compressed, 2-flowered; lower flower hermaphrodite; upper staminate 
or reduced to a sterile glume, 14 to 2 lines long (exclusive of awns and hairs). 
Glumes 4; first one-third to one-half the length of the spikelet, lanceolate, 
acute or obtuse, membranaceous, l-nerved, nerve scabrous; second about two-thirds 
the length of the spikelet, lanceolate, acute, membranaceous, its single nerve scab- 
rous and produced into an aristate point nearly reaching the apex of the spikelet; 
rachilla pilose between the second and third glumes; third (flowering) obovate, 
compressed, apex narrowed making the glume hooded, pilose in irregular areas 
on the back, or glabrous, the margin short-pilose below, and on either margin 
near the apex long-pilose, hairs two-thirds as long as the spikelet, apex of the 
glume produced into a slender, scabrous, straight, not twisted awn two to three 
times the length of the spikelet; sterile glume similar in shape to the flowering 
glume, but smaller and glabrous, with a nearly equalawn. Rudiment of a third 
flower sometimes present. 
Flower hermaphrodite. Palet oblanceolate, 2-nerved, margins folded inward. 
Stamens 3; anthers small, sagittate-lanceolate, + line long; stigmas small, cylin- 
drical. Flower of sterile glume sometimes wanting, sometimes represented only 
by a palet, rarely by stamens also. 
Grain narrowly fusiform, acute at both ends, 2 to 1 line long, inclosed in the 
flowering glume, the rachilla @isarticulating above the second glume. 
Puate XXIX; a and 3, spikelet, rachilla broken at the point of disarticula- 
tion, and the parts spread open. . Ina the shorter glume should be on the right and 
below, the longer on the left. In 6b, the sterile glume and the rudiments of a 
third flowering glume are shown. 
This species is common in the southern parts of this region, and still more 
common in Mexico 
