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.
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. The first and the second glumes are lanceolate narrowed into short stiff awns, equal or the second a little longer, hyaline glabrous, strongly keeled about 1/6 inch long or a little less. The succeeding glumes third, fourth and fifth are very much shorter than the first two glumes, about 1/10 inch or less, ovate-oblong, subacute, white, membranous with a strong greenish nerve along the keel and two short ones close to the margin, paleate; palea is shorter than the glume, membranous, oblong-obtuse, minutely 2-toothed, 2-nerved and 2-keeled. Stamens are three with small anthers. Stigmas are white when young and purple when mature. Lodicules are very minute. The grain is pale, brownish yellow, ellipsoidal-oblong, subacute, trigonous, rough and never smooth, with a shallow groove on the dorsal side; the embryo is about one-third the length of the grain.
This grass grows abundantly in cultivated dry fields all over the Presidency. The spikes when mature become very rough and give an acid taste. Cattle greedily eat this grass when young, but when old and in full flower some cattle do not like it so much.