Derivation
Aristida L., Sp. Pl. 1: 82 (1753); from the Latin arista (an awn).

utilis- from Latin utilis (useful). Peduncles used for the manufacture of hats.

Common synonyms
Aristida streptachne Domin

Habit
Perennial, tufted. Culms 53–130 cm tall. Mid-culm internodes smooth or scaberulous, pubescent. Mid-culm nodes glabrous. Lateral branches simple or sparsely branched or branched. Leaf-sheaths smooth or scaberulous, glabrous on surface. Ligule a fringe of hairs, 0.3–0.5 mm long. Leaf-blades curled or flexuous, flat or conduplicate or involute or convolute, 10–21 cm long, 1.5–2 mm wide. Leaf-blade venation comprising 3 vascular bundles. Leaf-blade surface smooth or scaberulous, glabrous or pubescent.

Inflorescence
Inflorescence compound, a panicle. Panicle open, lanceolate, 15–48 cm long, 1–6 cm wide. Primary panicle branches appressed, moderately spaced, 2–3-nate, 4–8.5 cm long, naked below or bearing spikelets almost to the base. Panicle branches scabrous, glabrous or pubescent.

Spikelets
Spikelets solitary. Fertile spikelets 1-flowered, comprising 1 fertile floret, without rhachilla extension, lanceolate, laterally compressed, compressed slightly, 8–20 mm long, breaking up at maturity. Spikelets disarticulating below each fertile floret. Floret callus evident, 0.4–0.7 mm long, pubescent, acute, hairs 1 mm long.

Glumes
Glumes persistent or lower deciduous, upper persistent, similar, thinner than fertile lemma. Lower glume lanceolate, 7.3–16 mm long, 90% length of upper glume, membranous, 1-keeled, 3–5-nerved. Lower glume surface smooth to scabrous, glabrous. Lower glume apex acute or acuminate, awned. Lower glume awn 2.5–4 mm long. Upper glume lanceolate, 8.3–17 mm long, 90–100% of length of adjacent fertile lemma, membranous, 1-keeled, 1-nerved. Upper glume lateral nerves absent. Upper glume surface glabrous. Upper glume apex entire, acute or acuminate, awned. Upper glume awn 2.5–4 mm long.

Florets
Fertile lemma lanceolate, subterete, 8–20 mm long, coriaceous, 3-nerved. Lemma surface scabrous, rough above, glabrous or pubescent. Lemma margins involute, covering most of palea. Lemma apex acute, 1–3-awned. Median (principal) awn geniculate or 3-branched, 14–40 mm long overall, 9–31 mm long, with a twisted column, persistent. Column 5–9 mm long, glabrous or puberulous. Lateral lemma awns absent or present, 0–10 mm long, shorter than principal, 10–30% of length of principal. Palea 20% of length of lemma, without keels. Anthers 3, 1.4–1.5 mm long. Grain with adherent pericarp, grooved. Embryo 25–50% of length of grain. Hilum linear, 25% of length of caryopsis.

Continental Distribution:
Australasia.

Australian Distribution:
Northern Territory, Queensland.

Northern Territory: Darwin & Gulf. Queensland: Cook, North Kennedy, Port Curtis, Burnett.

Classification. (GPWG 2001):
Aristidoideae

Notes
Native. There are two varieties.

Aristida utilis F.M.Bailey var. utilis
Two records from the "top end" of the Northern Territory, a number of records from coastal Queensland and a few records from Papua New Guinea. Eucalyptus woodland in granite sand country. Flowering and fruiting January to August.

Aristida utilis F.M.Bailey var. grandiflora B.K.Simon
Known only from Andoom, Cape York Peninsula, Queensland. Collected from a regenerated mine site. Flowering and fruiting April.
This is a giant form of Aristida utilis, which may be a reflection of its proximity to alumina deposits.