Eriachne rara R.Br. 1810

pronounced: air-ree-ACK-kee rah-rah

(Poaceae —  the grass family)

common name: Wanderrie Grass

Eriachne Eriachne raraseed heads Eriachne raraseed heads detailis derived from two Greek words, εριον (erion), wool, and αχνη (achné), chaff, possibly referring to the fact that the florets are hairy; rara is from the Latin rarus, of a loose texture. Wanderrie is found in the common name of most of the Eriachne species of grasses, as well as in the common names of various other plants found across Northern Australia. The derivation of Wanderrie is unknown, and the only place bearing the name I have been able to find is Wanderrie Well, near Marble Bar in Western Australia.

Wanderrie grasses may be annuals or perennials, rhizomatous or tufted. The inflorescence is a panicle, which may be open or contracted. The spikelets are solitary, and the glumes spread at maturity to show two bisexual florets, that may or may not have awns. The glumes often persist after the flowers have fallen.

Eriachne raragrain with awns This species occurs down the eastern coastal regions of  Queensland and northern NSW, mainly between about 20 º and 30º S latitude, usually on the coastal plains and the off-shore islands. It is found on both deep and shallow soils, that are sandy, or sometimes gritty or stony. and sometimes on hill slopes or ridges, Melaleuca swamps, and seasonal water channels. The plants photographed were near the track on The Forts walk.

The grass is perennial, with culms from 16 – 75 cm tall, with bearded mid-culm nodes. The ligule has a fringe of very short hairs, only about 0.5 mm long. The leaf blades are involute, 4 – 20 cm long by up to 5 mm wide, the surface scaberulous, indumented.

The compound inflorescence is a panicle, elliptic or oblong, 3 – 10 cm long, 0.5 – 5 cm wide.

The spikelets are pedicelled; The fertile spikelets have 2 flowers, both of which are fertile. The glumes are similar, thinner than the fertile lemma. The lower glume is ovate, membranous,  without keels, and with a smooth, glabrous or indumented surface. The upper glume is also ovate, 5 – 9 mm long, membranous, without keels, with a surface similar to that of the lower glume.

The fertile lemma of the florets is 3 – 5.5 mm long, without a keel. The lemma surface is indumented, the apex awned. The median (principal) awn is 12 – 30 mm long. The palea apex is erose or dentate, 2-awned; the grain is 2 – 3 mm long,

The chief distinguishing features of the species are the dense indumentum, the loose, often tuberculate and hairy panicle, the sparsely hairy long-acuminate glumes, the short, often red, florets with appressed lemma and palea, the relatively long callus, the awned lemmas obscured by hairs, and the beaked bifid palea.

Eriachne rara flowers and fruits usually in February – May, although the season can extend to September.

Photographs taken on The Forts walk, 2013

Page last updated 28th November 2016

 

 

 

 

 

 

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