Common name
Many Headed Wiregrass

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

caput-medusae- from the Latin caput (head) and Medusa (monster with snakes for hair), alluding to the shape of the inflorescence resembling the head of the Medusae of Greek mythology. Inflorescence a spike-like panicle and the spikelets with long trifid, twisted awns.

Common synonyms
Aristida vagans Cav. var. compacta Benth.
Aristida ramosa R.Br. var. compacta Benth.

Habit
Perennial, tufted. Culms 33–85 cm tall. Mid-culm internodes smooth or scaberulous, glabrous. Mid-culm nodes glabrous. Lateral branches branched. Leaf-sheaths smooth or scaberulous, glabrous on surface. Ligule a fringe of hairs, 0.5 mm long. Leaf-blades straight, conduplicate or involute or convolute, 2–4 cm long, 0.5–1 mm wide. Leaf-blade venation comprising 0 vascular bundles. Leaf-blade surface scabrous.

Inflorescence
Inflorescence compound, a panicle or a panicle. Panicle contracted, lanceolate or ovate, 3.9–8 cm long, 1–5 cm wide. Primary panicle branches 4–9 cm long, bearing spikelets almost to the base. Panicle branches scaberulous or scabrous, with prominent pulvini.

Spikelets
Spikelets solitary. Fertile spikelets 1-flowered, comprising 1 fertile floret, without rhachilla extension, lanceolate, terete, 6–9.5 mm long, breaking up at maturity. Spikelets disarticulating below each fertile floret. Floret callus elongated, 0.8–1.1 mm long, pubescent, acute.

Glumes
Glumes persistent, similar, thinner than fertile lemma. Lower glume lanceolate, 2.7–5 mm long, 66% length of upper glume, membranous, 1-keeled, 1-nerved. Lower glume lateral nerves absent. Lower glume surface asperulous or scabrous, glabrous. Lower glume apex obtuse to acuminate. Upper glume lanceolate, 4–8 mm long, 66–80% of length of adjacent fertile lemma, membranous, 1-keeled, 1-nerved. Upper glume lateral nerves absent. Upper glume surface smooth to scabrous, glabrous. Upper glume apex entire or erose, emarginate or obtuse or acute or acuminate or cuspidate, muticous or mucronate.

Florets
Fertile lemma lanceolate, subterete, 6–9.5 mm long, coriaceous, pallid or light brown, concolorous or mottled with last colour, 3-nerved. Lemma surface smooth or scabrous, rough generally. Lemma margins convolute, covering most of palea. Lemma apex acute, 3-awned. Median (principal) awn spreading, flat below, 7–13 mm long, without a column, persistent. Lateral lemma awns present, spreading as much as principal, 6–12 mm long, subequal to principal, 85–90% of length of principal. Palea 20% of length of lemma, without keels. Anthers 3, 1.3 mm long. Grain with adherent pericarp, terete, not grooved, 4–6.1 mm long. Embryo 25–50% of length of grain. Hilum linear, 40% of length of caryopsis.

Continental Distribution:
Australasia.

Australian Distribution:
Queensland, New South Wales.

Queensland: Burnett, Darling Downs, Leichhardt, Maranoa, Mitchell, Moreton, Port Curtis, North Kennedy, South Kennedy, Warrego, Wide Bay. New South Wales: North-Western Slopes, North-Western Plains.

Classification. (GPWG 2001):
Aristidoideae

Notes
Native. Central and south-eastern Queensland to northern New South Wales.
Acacia, and Eucalyptus communities on loams, sands and rocky soils. Flowering and fruiting all year. Aristida caput-medusae has very distinctive morphological facies, including a knotty rootstock, fastigiately branching culms and a small uniquely shaped panicle, ovate in outline, resembling the head of the Medusa of Greek mythology, from which it derives its name. It has small spikelets similar to Aristida vagans in that the lemma extends beyond the glumes but differs from this species in that the panicle is smaller and regular in outline.

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