No. 9. - 
THURBERIA ARKANSANA Bentham. 
Plant annual. 
' Rootstock none. Roots very slender. 
Culms erect, simple or branching from the base, slender, commonly 9 to 18 
inches high, sometimes depauperate, glabrous. 
Leaves of the stem 3 to 5; sheaths contiguous, glabrous or sparingly villous, 
the margin villous-ciliate; blade flat, 1 to 4 inches long, 1 to 2 lines broad, flaccid, 
scabrous, and usually sparingly minutely villous-pubescent; ligule about 4 line 
long, the apex narrowly fringe 
Inflorescence a panicle at first partly sheathed, finally pedunculate, 3 to 6 
inches long; branches slender, seldom exceeding 1 inch in length; spikelets borne 
singly on pedicels 14 lines long or shorter. 
Spikelets linear, 14 to 2 lines long (exclusive of the awn), nearly terete, jointed 
to the pedicel below the glumes. 
Glumes 3; first and second of equal length, similar, lanceolate, acute, green, 
nerveless or obsoletely 3-nerved, scabrous-pubescent without, apices slightly sep- 
arated; third (flowering) not green except the 3 nerves, glabrous, rather thick, 
lanceolate, folded and compressed, awned on the back a little below the apex; apex 
cleft half-way to the origin of the awn; awn slender, $to 4 inch long, little twisted, 
abruptly bent at the middle. 
Flower single, hermaphrodite; rachilla prolonged above the flower (!) into | 
a minute filiform rudiment about 4 line long, naked or surmounted by a minute 
scale; palet very thin, hyaline, narrowly linear, 2-nerved; lodicules 2, about 4 line 
long; stamens 3, anther oblong, about 2 line long; stigmas cylindrical, on short 
distant styles. 
Grain linear-oblong, atic ied closed within the glumes, the spikelet disartic- 
ulating eee them. 
Plate IX; a, first (on the left) and second glumes; b, flowering glume and 
flower. The rudimentary prolongation of the rachilla shown in b is usually twice 
as long and is inserted at a point on the axis near the middle of the base of the 
palet, not on the flowering glume, as shown in the figure. 
7 
