Common name
Mulga Grass
Mulga Mitchell
Window Mulga Grass

Derivation
Thyridolepis S.T.Blake, Contr. Queensland Herb. 13: 25 (1972); from the Greek thyridos (a window) and lepis (a scale), alluding to the peculiar lower glume.

mitchelliana- in honour of Thomas Livingstone Mitchell (1792–1855), Scots-born Australian surveyor and explorer.

Published in
Contr. Queensland Herb. 27 :13 (1972).

Common synonyms
Neurachne mitchelliana Nees

Habit
Perennial, tufted. Basal leaf sheaths pilose. Culms erect, 20–60 cm tall. Mid-culm internodes pubescent. Mid-culm nodes pubescent. Ligule a fringe of hairs. Leaf-blades 1–6 cm long, 3–5 mm wide, rigid. Leaf-blade midrib indistinct. Leaf-blade margins ciliate. Leaf-blade apex acute or acuminate.

Inflorescence
Inflorescence solid, a panicle. Panicle spiciform, linear, 2–4 cm long. Primary panicle branches accrescent to a central axis, with lateral stumps on axis. Panicle axis angular, pubescent.

Spikelets
Spikelets solitary. Pedicels oblong, pubescent, tip discoid. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile or male, upper fertile, without rhachilla extension, elliptic, dorsally compressed, 5–7 mm long, falling entire. Spikelet callus pubescent. Rhachilla internodes elongated between glumes.

Glumes
Glumes dissimilar, thinner than fertile lemma. Lower glume lanceolate, 5–7 mm long, 100% of length of spikelet, coriaceous, 3–5-nerved. Lower glume lateral nerves ribbed. Lower glume surface with a longitudinal median groove. Lower glume surface fenestrate, glabrous or pubescent, with a dorsal tuft of hair. Lower glume apex obtuse. Upper glume elliptic, 4.5–6.5 mm long, coriaceous, with membranous margins, 5–7-nerved. Upper glume lateral nerves ribbed. Upper glume surface tuberculate, rough below, glabrous or pubescent. Upper glume margins tuberculate. Upper glume margins setose. Upper glume apex obtuse.

Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret ovate, 80% of length of spikelet, herbaceous, 5-nerved, pubescent, hairy between nerves, cuspidate. Fertile lemma ovate, 4 mm long, chartaceous, 3-nerved. Lemma apex cuspidate. Palea 2-nerved. Anthers 3. Stigmas 2.

Continental Distribution:
Australasia.

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

Western Australia: Giles, Helms, Ashburton, Austin, Irwin, Avon, Coolgardie. Northern Territory: Central Australia North, Central Australia South. South Australia: North-western, Lake Eyre, Gairdner-Torrens Basin, Flinders Ranges, Eastern, Eyre Peninsula. Queensland: North Kennedy, South Kennedy, Leichhardt, Darling Downs, Gregory North, Gregory South, Warrego, Maranoa. New South Wales: Central Coast, North-Western Slopes, Central-Western Slopes, South-Western Slopes, North-Western Plains, South-Western Plains, North Far Western Plains, South Far Western Plains.

Classification. (GPWG 2001):
Panicoideae: Neurachneae

Notes
Native. In semi-arid shrub woodlands, arid and semi-arid low woodlands, shrub steppe shrublands, acacia shrublands, eucalypt shrublands, arid tussock grasslands, arid hummock grasslands, and coastal grasslands. Flowers mostly Mar.–Sept., but sporadically throughout the year. The association of long villous hairs with setaceous hairs on the submargins of the upper glume distinguishes this species. However, only spikelets on the upper part of the inflorescence should be used, as drastic spikelet dimorphism in a single inflorescence occurs. Additional important characters include spikelet length, main axis length and length of the submarginal hairs.