Ischaemum aristatum L.

Global description

Ischaemum aristatum is a vivacious grass, tufted, supple with culms upright or prostrate at the base, 30 cm to 80 cm high, more or less branched in the lower part. The leaves are erect or spreading. The sheath is abundantly ciliated, particularly along the margins and the node is equipped with large white hairs. The lamina is linear to lanceolate of quite variable size of 5 to 30 cm long and 4-10 mm wide, acuminate at the top. The ligule is membrano-ciliated. The inflorescence is composed of two racemes, golden yellow, closely juxtaposed of 4 to 7 cm long, then separated and obliquely erect at maturity. The racemes are fake spikes, with very fragile axis formed of thick articles that easily dislocate when dry. Each article consists of two spikelets of which one is sessile and fertile, 5 to 8 mm long, and the other is pedicelate sterile of 4 to 6 mm long. The hull are dissimilar. The lower hull is as long as spikelet and bicariniate . Upper glume is lanceolate as long as the spikelet, leathery and cariniate.
 
General habit

Plant tufted clumps forming spreading, flexible, erect stubble or prostrate at the base then become upright, reaching 80 cm in height.
 
Underground system

The roots are dense fibrous and plant have short rhizomes.
 
Culm

The culm is cylindrical or caniculate, smooth, hairless, with glabrous or hairy nodes, more or less branched in the lower part.
 
Leaf

The leaves are simple, alternate. The sheath may be smooth, but usually abundantly ciliated, especially along the margin (hence the name Mauritian Creole, silver grass) and the node is equipped with large white hairs. The ligule is membrano- ciliated, scaly, measuring 3-4 mm long. The lamina is linear lanceolate, erect then drooping, 5 to 30 cm long and 4-10 mm wide, acuminate at the top and narrowed base. Both sides are glabrous or hairy with scattered hairs. The margin is smooth or scabrous.
 
Inflorescence

The inflorescence is first included in the final leaf sheath then ultimately significantly externalized, made up of two geminal racemes, first joined closely taking the appearance of a erect cylindrical spike of 4 to 7 cm long then separated, obliquely erect. The spine is angular, scabrous and breaking easily at nodes.
 
Spikelet

Each section consists of two kinds of similar morphology spikelets: one sessile and fertile of 5 to 8 mm long, oblong, appressed against the spine, and the other pedicellate, sterile, sturdy stalk, short and stocky of 4 to 6 mm, almost as long as the sessile spikelet. For each spikelet, the lower glume, of the size of the spikelet is bicariniate, muticate or shortly awned (edge ​​0-3 mm long). The upper hull is as long but narrower, laterally compressed, keeled on the back. Lemma of the fertile flower, shorter than glumes and deeply forked up half, have in the sinus an untwisted edge, straight or angled towards the middle, about 1 to 10 mm long, exceeding the spikelets.
 
Grain

The grain is ellipsoid, 2 mm long and 1 mm wide, clad.
 

https://www.gbif.org/fr/species/4113668