icules; 8. first glume of the pedicelled
spikelets.]

=Ischaemum rugosum, _Salisb._=

This is an erect annual grass with tufted, leafy, compressed stems
varying in length from 10 inches to 2 feet.

The _leaf-sheath_ is glabrous, loose and compressed, with a membranous
auricle confluent with the truncate _ligule_. _Nodes_ usually glabrous
but sometimes also puberulous.

The _leaf-blade_ is narrow, linear-lanceolate, flat, base contracted,
flaccid, acuminate, rounded at the base, glabrous or sparsely hairy on
both the surfaces; the topmost leaf is often reduced to an inflated
sheath enclosing the inflorescence partially.

[Illustration: Fig. 132.--Ischaemum rugosum.

1. A part of the raceme showing sessile spikelets with reduced
pedicelled spikelets; 2. a sessile spikelet and a well developed
pedicelled spikelet; 3. a reduced pedicelled spikelet; 4, 5, 6 and 8.
the first, second, third and the fourth glume of the sessile spikelet; 7
and 9. palea of the third and fourth glumes of the sessile spikelet; 10.
ovary.]

The racemes are usually two, erect, fragile, 1 to 3 inches long with a
slight thickening of the peduncle below the inflorescence; the joints
are 1/3 to 2/3 as long as the sessile spikelets; trigonous and
subclavate, and with long hairs on one side. The _spikelets_ are
linear-oblong, glabrous or villous, 1/8 to 1/4 inch long, sessile and
stalked spikelets close together; the pedicel of the stalked spikelet is
thick about 1/3 or less than the length of the sessile spikelet, ciliate
on one side, confluent with the thick callus of the sessile spikelet,
which is sparsely bristly. The _sessile spikelet_ consists of four
glumes and is awned. The _first glume_ is concave, pale yellow, shining
and cartilaginous to about 2/3 its length from the base, and the upper
third is membranous, dimidiately ovate; at the back in the cartilaginous
portion, there are three to six deep convex smooth ridges running across
the glume; the membranous tip is thin and with anastomosing green veins;
the margins of this glume are thick, narrowly incurved, ciliolate, and
with a narrow wing on the outer margin. The _second glume_ is
oblong-lanceolate or lanceolate, coriaceous, acuminate, scaberulous,
keeled and laterally compressed and on the keel just below the tip there
is a narrow ciliate wing. The _third glume_ is ovate-lanceolate,
hyaline, acuminate 1- to 3-veined, male or empty, with a narrow hyaline
palea. The _fourth glume_ is