Derivation
Triodia R.Br., Prodr. 182 (1810); from the Greek treis (three) and odous (tooth), referring to the 3-toothed or 3-lobed lemmas.

inutilis- from the Latin in- (not) and utilis (useful). Not useful for domestic grazing animals.

Published in
Austral. J. Bot. 1: 163 (1953).

Habit
Perennial, densely tufted. Stolons present. Culms 30–130 cm tall. Mid-culm nodes pubescent. Leaf-sheaths without exudate, indistinctly or striately nerved. Leaf-sheath auricles absent. Ligule a fringe of hairs. Leaf-blade base with a false petiole. Leaf-blades straight, aciculate, conduplicate, 5–21(–35) cm long, 0.7–2 mm wide, rigid. Leaf-blade venation without layer of subepidermal sclerenchyma masking nerve striation. Leaf-blade apex pungent.

Inflorescence
Inflorescence compound, a panicle. Panicle open or contracted, linear or elliptic or ovate, 9.5–26 cm long, 2–6 cm wide. Panicle branches scaberulous.

Spikelets
Spikelets solitary. Pedicels scaberulous. Fertile spikelets many flowered, comprising 7–9 fertile florets, with diminished florets at the apex, oblong or ovate, laterally compressed, obtuse, 6–10(–13) mm long, 3.5–5 mm wide, breaking up at maturity. Spikelets disarticulating below each fertile floret. Spikelet callus bearded, base obtuse.

Glumes
Glumes persistent, similar, thinner than fertile lemma. Lower glume lanceolate or oblong, 3.5–6.5 mm long, equalling upper glume, scarious or cartilaginous, 3–5-nerved, midnerve scabrous. Lower glume surface glabrous. Lower glume apex entire, acute or acuminate, muticous or mucronate. Upper glume lanceolate or oblong, 3.5–6 mm long, 100% of length of adjacent fertile lemma, scarious or cartilaginous, 3–5-nerved, midnerve scabrous. Upper glume surface glabrous. Upper glume apex entire, acute or acuminate, muticous or mucronate.

Florets
Fertile lemma oblong, 4–5(–7) mm long, cartilaginous or coriaceous or indurate, 5–9-nerved. Lemma midnerve pubescent. Lemma lateral nerves in close groups (of 3). Lemma surface hirsute. Lemma margins pubescent, hairy below. Lemma apex lobed, 3-fid, with triangular lobes, with lobes 3.5 mm long, acuminate, incised 50% of lemma length. Palea elliptic, 4–4.5 mm long. Palea keels conspicuously winged. Palea surface glabrous. Apical sterile florets resembling fertile though underdeveloped. Anthers 3, 1.7–2 mm long.

Continental Distribution:
Australasia.

Australian Distribution:
Western Australia, Northern Territory.

Western Australia: Gardner, Fitzgerald, Hall. Northern Territory: Victoria River, Barkly Tableland.

Classification. (GPWG 2001):
Chloridoideae: Triodieae

Notes
Native. On crests and slopes of hills, mesas, plateaux, gorges, domes, ridges and outcrops; in skeletal or shallow, sandy often rocky or stony, undulating soils; in association with sandstone, limestone, laterite, shale and volcanic rocks; flowers Mar.–Aug., Dec. and Feb.