Tetrarrhena laevis R. Br. Prodr. 210(1810).
Classification. (GPWG 2001) : Subfamily Ehrhartoideae. Tribe Ehrharteae.
Type of Basionym or Protologue Information: Australia, Lewin & Wilson promontories: Brown 6169 (K iso).
Key references (books and floras): [1810]. R.Brown, Prodromus (210), [1878] G.Bentham, Flora Australiensis 7 (554), [1952] C.A.Gardner, Flora of Western Australia 1 Gramineae (21), [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia, [2002] J.Wheeler, N.Marchant & M.Lewington, Flora of the South West (437), [2009] A.Wilson (ed.). Flora of Australia, Vol 44A. Poaceae 2 (380).
Illustrations: [1952] C.A.Gardner, Flora of Western Australia 1 Gramineae (17 & 20, Pl. 3), [2009]. A.Wilson (ed.), Flora of Australia 44A: Poaceae 2 (372, Fig. 50).
Habit. Perennial. Rhizomes present, short. Stolons absent or present. Culms erect, 25–70 cm tall, wiry. Leaf-sheath auricles absent. Ligule an eciliate membrane or a fringed membrane, a ciliolate membrane, 0.1–0.3 mm long, membranous. Leaf-blades flat, 6–20 cm long, 2–8 mm wide. Leaf-blade surface scabrous.
Inflorescence. Inflorescence solid, a raceme or a panicle. Panicle linear, 2.4–9 cm long.
Spikelets. Spikelets pedicelled. Fertile spikelets 1-flowered, comprising 2 basal sterile florets, comprising 1 fertile floret(s), without rachilla extension, oblong or ovate, laterally compressed, 7–8 mm long.
Glumes. Glumes similar, thinner than fertile lemma. Lower glume oblong, chartaceous, without keels, 5–9 -nerved. Upper glume oblong, 3.4–4.8 mm long, chartaceous, without keels, 5–7 -nerved. Florets. Basal sterile florets 2 or more, barren, without significant palea. Lemma of lower sterile floret 100 % of length of spikelet, cartilaginous, 1-keeled, 5 -nerved, muticous. Lemma of upper sterile floret 4.7–6.7 mm long, muticous.
Fertile lemma 4.5–6 mm long, keeled, 9 -nerved. Lemma surface glabrous. Palea 1 -nerved, 1-keeled. Lodicules present. Anthers 4–6.
Continental Distribution: Australasia.
Australian Distribution: Western Australia.
Western Australia: Drummond, Dale, Menzies, Warren, Eyre.
Notes. Recorded from organic sandy loam soils or on granite in open eucalypt forest or in scrub. Flowers Sept.-Jan.
