Setaria pumila

yellow bristle-grass


Setaria pumila

(Poir.) Roem. & Schult. 1825

pronounced: set-TARE-ee-uh POO-mill-uh

(Poaceae — the grass family)


common names: yellow bristle-grass, yellow foxtail

Setaria is derived from the Latin seta, a bristle, referring to the bristly inflorescences of the genus; pumila is from pumilus, dwarfish, little.

There are about 110 species of Setaria found in tropical and warm regions of the world. S. pumila occurs in the tropics worldwide, and often in temperate zones, and is probably native to Micronesia. In the tropics, it is usually found in areas where the mean annual rainfall exceeds 500 mm. It has become a weed in many areas, infesting crops, roadsides, waste areas, ditches, and sometimes grassland. It succeeds in any well-drained soil in full sun.

In parts of New Zealand it has established itself in dairy pastures, taking over up to 40% of the area, and affecting milk production.

This is an annual plant, and is without rhizomes.

In the seedling, the leaves are rolled in the bud; the leaf sheathes are hairless, but the leaf blades have long silky hairs on the upper surface near the leaf base.

There is a fibrous root system, and the stems do not root at the nodes. The glabrous stems are erect and often flattened, can reach up to about 90 cm in height, and often have a reddish tint at the base.

Leaf blades may reach up to 30 cm in length and up to 1 cm or a little more in width, and are scabrous. They have long silky hairs at the bases of the leaves, but are otherwise glabrous. There are no auricles, and the ligule is a fringe of hairs 2 mm or so long, often very difficult to see with the naked eye.

The inflorescence is long-exserted, spikelike, erect, dense, continuous, oblong or cylindrical, 1 - 15 cm long (sometimes as long as 20 cm); the branches are close, the bristles straight or subflexuous, very unequal. The spikelets are broadly oblong to elliptic or ovate, 3 mm or a little more in length, often subtended by aborted spikelets and 4-12 bristles up to 1 cm long. The lower glume is about a third of the length of a spikelet, broadly ovate, obtuse to subacute. The lower lemma is usually sterile, as long as the spikelet, and membranous. The palea is subequal to the lemma, broadly elliptical, and acute. The upper lemma is bisexual, the same length at the spikelet, strongly transversely rugose, sometimes apiculate; the palea is similar.

The seeds are barbed, and are spread by being carried in fur, feathers or clothing.

The grass can be made into reasonably good hay. In Lesotho sheaves of grain are tied together using rope made from culms of the grass twisted together. In some areas the grass plays an important part in stabilising poor soil to protect it from erosion.

The seeds can be cooked and eaten as a sweet or savoury food in much the same way as rice; or it can be ground into a flour used for making porridge, cakes, puddings, etc.


Photographed at Nelly Bay 2013
Page last updated 3rd April 2019