Hemarthria altissima (Poir.) Stapf & C.E.Hubb.

Global description

Hemarthria altissima is a vivacious stolonniferous grass with prostrate culms. The leaves are linear with membranociliated ligule. The inflorescence is constituted of fasciculate cylindrical racemes whose rachis breaks up into irregular segments. The pedicelled spikelets are male, linear, the sessile spikelets are fertile, lanceolate and compressed, of the same length as the pedicellate spikelets. Sessile spikelet is formed of a sterile basal flower and a fertile superior flower.

General habit

Vivacious grass creeping and strongly stolonniferous, developing into spots. Prostrate culms up to 100 to 250 cm long.

Underground system

Root fasciculated at the base of the plant and many adventitious roots developing at the nodes in contact with the ground.

Culm

The culm is prostrate, branched, 100 to 250 cm long, it is knee and ascending at the end. It is compressed, with a diameter of 2 to 4 mm. The knots are glabrous.

Leaf

The sheath is open, glabrous but ciliated on the margins. The ligule is short, membranous with ciliate top. The blade is flat or folded, linear, 5 to 20 cm long and 3 to 5 mm wide. Prefoliation is folded. The faces are hairless, the margin is smooth with some long hairs at the base. The apex is acute and the base is the same width as the sheath. The leaves turn red brown when drying.

Inflorescence

The inflorescence consists of erect lateral and terminal racemes outgoing well from the sheaths of leaves. They are solitary or fasciculated by 2 to 4 linear sub-cylindrical slightly compressed laterally, and slightly arched. They are hairless, 5 to 12 cm long and 2 to 3 mm in diameter. The rachis is disarticulate in irregular segments, flattened with a smooth margin. The internodes are cuneiform. Article and pedicel are welded into a piece that forms a cavity in which the sessile spikelet is housed.

Spikelet

The spikelets are in pairs, one pedicelled is male, the other sessile is fertile. The sessile spikelet is lanceolate, dorsally compressed, 5 to 7 mm long, glabrous with triangular callus. Base truncated and attached obliquely. Glumes are dissimilar, slightly longer than lemmas and paleas. The lower glume is lanceolate, herbaceous with two winged keels, visible intercarenal nerves, the apex is emarginate or obtuse. The upper glume is oblong, membranous, not carinated but trinerved with obtuse or acute apex. The lower floret is neutral, consisting of an oblong hyaline lemma with 2 veins, mutic, the palea is absent. The upper floret is fertile, shorter than the glumes, consisting of an oblong, hyaline lemma without keel or vein, obtuse apex and a hyaline palea. The pedicelled spikelet is the same length as the sessile one but narrower, consisting of two herbaceous glumes with acute apex and two lemmas hyaline shorter than the glumes. At maturity, the two spikelets fall together with the fragment of rachis which is disarticulated.

Grain

The grain is oblong to obovoid, 2 mm long, reddish in color and slightly dorsally compressed.

Origin

Hemarthria altissima is native to the old world (Africa, Asia).

Worldwide distribution

It is present in tropical and southern Africa, in the Indian Ocean, in Asia (Arabia, China, India, Burma, Vietnam, Borneo, Malaysia), also in southern Europe (Italy, Turkey). It has been introduced in tropical America and the West Indies.

https://www.gbif.org/species/2706322