Common name
Lobed Spinifex
Hard Spinifex

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

basedowii- in honour of Herbert Basedow (1881–1933), South Australian geologist.

Published in
Repert. Spec. Regni Veg. 15: 356 (1918).

Habit
Perennial, densely tufted. Stolons present. Culms 15–130 cm tall. Leaf-sheaths woolly. Leaf-sheath auricles absent. Ligule a fringe of hairs. Leaf-blade base with a false petiole. Leaf-blade base petiole 0.2–0.4 cm long. Leaf-blades straight, aciculate, conduplicate, (2–)5–25 cm long, 0.7 mm wide, rigid, without exudate. Leaf-blade venation without layer of subepidermal sclerenchyma masking nerve striation. Leaf-blade apex pungent.

Inflorescence
Inflorescence compound, a panicle. Panicle contracted, linear, (3–)6–13(–16) cm long, 1–1.5 cm wide. Primary panicle branches appressed.

Spikelets
Spikelets solitary. Fertile spikelets many flowered, comprising 5–6 fertile florets, with diminished florets at the apex, oblong, laterally compressed, 7–18 mm long, breaking up at maturity. Spikelets disarticulating below each fertile floret. Spikelet callus 0.5–0.6 mm long, bearded, base acute.

Glumes
Glumes persistent, similar, thinner than fertile lemma. Lower glume oblong, (4–)6–10 mm long, equalling upper glume, scarious, 7–13-nerved. Lower glume apex entire, emarginate or truncate or obtuse or acute or acuminate, muticous or mucronate. Upper glume oblong, (4–)6–10 mm long, 100% of length of adjacent fertile lemma, scarious, 7–13-nerved. Upper glume apex entire, emarginate or truncate or obtuse or acute or acuminate, muticous or mucronate.

Florets
Fertile lemma oblong, 5.5–9 mm long, coriaceous or indurate, keeled below, 9–15-nerved. Lemma lateral nerves evenly spaced. Lemma surface pubescent or hirsute. Lemma margins ciliolate. Lemma apex lobed, 3-fid, with ovate lobes, with lobes 3–6 mm long, obtuse or acute, incised 66% of lemma length. Palea oblong or obovate. Palea keels wingless or winged, scabrous. Palea surface glabrous or hirsute. Apical sterile florets resembling fertile though underdeveloped. Anthers 3, 3–4.3 mm long.

Continental Distribution:
Australasia.

Australian Distribution:
Western Australia, Northern Territory, South Australia, Queensland, New South Wales.

Western Australia: Mueller, Canning, Keartland, Carnegie, Giles, Helms, Fortescue, Ashburton, Carnarvon, Austin, Eucla. Northern Territory: Barkly Tableland, Central Australia North, Central Australia South. South Australia: North-western, Lake Eyre, Nullabor, Flinders Ranges. Queensland: Burke, Gregory North, Gregory South, Mitchell. New South Wales: North Far Western Plains.

Classification. (GPWG 2001):
Chloridoideae: Triodieae

Notes
Native in the arid regions of Australia. Chiefly on flat to gently sloping and undulating sandplains, dunefields, dune swales and sandhills in deep, red or reddish-yellow, siliceous sands and sandy loams. Flowers all seasons.