Setaria australiensis  (Scribn. & Merr.) Vickery 1951

pronounced: set-TARE-ee-uh oss-trah-lee-EN-siss

(Poaceae – the grass family)

common name:  Scrub Pigeon Grass

Setaria setaria australiensisscrub pigeon grasssetaria australiensis seedheadsseedheadsis derived from the Latin seta, a bristle, referring to the bristly inflorescences of the genus; australiensis is botanical Latin for ‘of or from Australia’.

This is a grass with a very pretty seed-head, occurring in coastal districts of northern NSW and Queensland. There appear only to be isolated patches of it on Magnetic Island. The plant photographed was in the ‘track’ portion of Yule Street, Picnic Bay.

Setaria, the genus of pigeon grasses, includes both annuals and perennials, and these may be rhizomatous or stoloniferous or tufted or decumbent. The inflorescence looks like a spike, but is actually a contracted panicle. Setaria is very like Pennisetum and Cenchrus in appearance, but spikelets fall from this genus without the bristles attached, leaving the bristles attached to the rachis.

setaria australiensis floweringfloweringsetaria australiensis fruitingfruitingThere are about 100 species of the genus world-wide, in both tropical and temperate areas; 16 of these are found in Australia, of which 9 are not native, but have become naturalized.

In the right conditions Setaria australiensis can grow quite tall, forming large tufts to about 2 m high. It grows in shady forest or on river banks. Its rhizomes are short. The culms are generally from 100–200 cm long, 3–6 mm in diameter, 6-noded.  The culm internodes are elliptical in section. Lateral branches are lacking, or sparse. The leaves with their keeled sheaths are glabrous, smooth and striate. The ligule is densely bearded, 2–3 mm long; the blade is flat, 5–20 mm wide, and finely rough to the touch. The midrib is prominent beneath.

The panicle is long-exserted, contracted, rather dense, 6–20 cm long, with erect or erectly-spreading branches, and the bristles are straight to flexuous.

The tiny flowers have 3 anthers about 1 mm long. The fruits are grains with the pericarp adhering, ellipsoid in shape, a little over 2 mm long.

Photographs taken 2010, Picnic Bay

Page last updated 12th February 2017

 

 

 

 

 

 

Website by Abraham Multimedia