produced beyond the flowering
glumes and bearing an imperfect glume. There are four to five glumes.
The first two glumes are the longest, lanceolate, 1-nerved, keeled and
awned. The second glume is slightly longer than the first. The third and
the fourth glumes are very small, hyaline, broadly ovate, 1-nerved.
Lodicules are present. Stamens are three and anthers didymous and small.
Grain is narrowly ovoid and trigonous.

[Illustration: Fig. 210.--Dinebra arabica.

1. Full plant; 2. leaf showing the ligule.]

=Dinebra arabica, _Jacq._=

This grass is an annual with stems erect or with a geniculate base,
tufted, slender or stout; some of the lower nodes of the geniculate part
of the stems bear roots; the internodes are green or purple tinged and
glabrous.

The _leaf-sheath_ is thin, somewhat loose, usually glabrous, rarely
sparsely hairy. The _ligule_ is a short membrane irregularly cut at the
top. The _nodes_ are glabrous.

The _leaf-blade_ is linear, very finely acuminate, rough on both the
surfaces, thinly and very sparsely hairy; the base of the blade is
contracted and purple tinged towards the margin, midrib is prominent
with three or four main veins on each side; the margins are very finely,
closely serrate.

[Illustration: Fig. 211.--Dinebra arabica.

1 and 2. The front and back view of a portion of a spike; 3. spikelet;
4, 5 and 6. the first, second and third glumes; 7. palea of the third
glume; 8. lodicules, ovary and stamens.]

The _inflorescence_ is a long erect narrow pyramidal panicle varying in
length from 2 to 16 inches; the lower branches sometimes bear several
spikes and attain 6 inches in length; the _peduncles_ are short or long,
purple tinged and the main _rachis_ is smooth except at the top, angular
and grooved. The _spikes_ are numerous, greenish or purple tinged,
slender, erect or spreading or sometimes deflexed, opposite, alternate
or in fascicles of two to four varying in length from 1/4 to 2-1/2
inches; the _rachis_ of the spike is trigonous, flattened out ventrally
and with a ridge on the ventral side and the margins are scabrid.

The _spikelets_ are few to many in a spike, alternate, closely
imbricating, sessile, about 1/6 inch long including the awns, usually
three flowered, rarely less or four flowered; the _rachilla_ is very
slender, jointed at the base, produced and jointed between the flowering
glumes.

There are usually five _glumes_ in a spikelet and in some four or six.