Sporobolus pyramidalis P.Beauv.

Global description

Sporobolus pyramidalis is a dense tufted grass, with linear leaves that are narrow and convoluted. The ligule is membrano-ciliated and very reduced. The inflorescence is a long panicle with many erect to spreading branches. Spikelets are solitary, grouped along short branches. They are spindle-shaped, with a reduced lower glume, a short upper glume and a single flower. The grain is free of obovoid form.

Seedling

The seedling is rarely observable because it is a vivacious species that develops into a tuft. It loses its leaves during the dry season, leaving only dry, non-fibrous stems and leaves. At the beginning of the rainy season, new leaves reappear at the base of the tuft. They are narrow, 5 to 10 cm long and 3 mm wide, with convoluted limb and rolled prefoliation. The sheath is finely ciliated on the margin. The ligule is membrano-ciliated and very reduced. The blade is glabrous, slightly scabrous on the margin.

General habit

The plant is tufted, dense. The axes are not branched and are interconnected by very short rhizomes. The plant is 30 to 160 cm tall.

Underground system

The roots are fasciculate.

Culm

The culm is cylindrical and glabrous, with a diameter of 2 to 5 mm. The nodes are glabrous and dark in color.

Leaf

The leaves are alternate. The sheath is glabrous, finely ciliated on the margin. It has a rounded hull. The ligule is membrano-ciliate, very reduced, high 0.3 mm. The lamina is linear, with a long pointed tip at the top. It is erect and usually convoluted or flat. It is 20 to 50 cm long and 3 to 10 mm wide. The margin is finely scabrous and both sides are glabrous.

Inflorescence

The inflorescence is a panicle 10 to 40 cm long and consists of many upright to spreading racemes arranged along the main axis but not in whorls. The branches of the base are 5 to 10 cm long. The spikelets are solitary, grouped by 2 to 10 along short secondary branches applied to the primary branches.

Spikelet

Spikelets are borne by a short pedicel of 0.3 mm. They are fusiform, 1.7 to 2 mm long. The lower glume is 0.2-0.6 mm long. The upper glume is 0,5-0,8 mm long, rounded at the apex and is less than a third of the length of the spikelet. Its dorsal rib is finely scabrous. The lemma and palea are acute, 1.5 mm long.

Fruit

The grain is obovoid, 0.8 to 1 mm long. It is free.

Origin

Sporobolus pyramidalis is native to America and tropical Africa, the Indian Ocean islands (Madagascar, Mauritius, Reunion) and the Arabian Peninsula.

Worldwide distribution

Sporobolus pyramidalis has been introduced into Burma and Australia.

https://www.gbif.org/fr/species/4117345