Derivation
Pseudopogonatherum A.Camus, Ann. Soc. Linn. Lyon. ser. 2, 68: 204 (1921); from the Greek pseudo (false) and pogonatherum, alluding to the similarity to the genus Pogonatherum.

irritans- from the Latin irrito (irritate). Callus sharp.

Published in
Ann. Soc. Linn. Lyon. ser. 2, 68: 205 (1921).

Common synonyms
Eulalia irritans (R.Br.) Kuntze

Habit
Annual. Culms erect, 50–150 cm tall, 6–8-noded. Mid-culm nodes glabrous. Lateral branches simple. Leaf-sheaths glabrous on surface. Ligule a fringed membrane, 0.3–0.5 mm long. Leaf-blades filiform, involute, 15–50 cm long, 1–3 mm wide, glaucous. Leaf-blade surface pubescent. Leaf-blade apex attenuate.

Inflorescence
Inflorescence with racemose branches. Racemes numerous, 3–20, digitate, erect or ascending, 3–6 cm long. Central inflorescence axis 1–3 cm long. Rhachis tough or fragile at the nodes, 0.4 mm wide, ciliate on margins. Raceme internodes linear. Raceme internode tip transverse.

Spikelets
Spikelets in pairs. Pedicels linear, angular, 1–2.5 mm long, ciliate. Companion spikelets bisexual. Fertile spikelets 2-flowered, comprising 1 fertile floret, without rhachilla extension, elliptic, dorsally compressed, 2.5–5 mm long, 0.5 mm wide, falling entire, deciduous from the base or with accessory branch structures. Spikelet callus 0.5–1 mm long, bearded, base acute, attached obliquely. Spikelet callus hairs 1–1.5 mm long.

Glumes
Glumes dissimilar, firmer than fertile lemma. Lower glume linear or lanceolate or oblong, 100% of length of spikelet, chartaceous, 2-keeled, 2-nerved. Lower glume surface convex or flat. Lower glume surface pilose, hairy generally. Lower glume hairs white. Lower glume apex dentate, 2-fid. Upper glume oblong, 100% of length of spikelet, 1-keeled, 1–3-nerved. Upper glume lateral nerves absent or obscure. Upper glume surface pilose. Upper glume hairs white. Upper glume apex awned. Upper glume awn 5–8 mm long.

Florets
Basal sterile floret 1, with vestigial lower floret. Fertile lemma linear or oblong or ovate, 1.5–2.5 mm long, hyaline. Lemma apex lobed, 2-fid, 1-awned. Median (principal) awn from a sinus, bigeniculate, 30–50 mm long overall, with a twisted column. Column ciliate, with 1.5–2 mm long hairs. Palea absent or minute. Anthers 3, 1 mm long. Grain 2 mm long.

Continental Distribution:
Tropical Asia, Australasia.

Australian Distribution:
Western Australia, Northern Territory, Queensland.

Western Australia: Gardner. Northern Territory: Darwin & Gulf. Queensland: Cook, North Kennedy, South Kennedy, Port Curtis.

Classification. (GPWG 2001):
Panicoideae: Andropogoneae

Notes
Native. Occurs sporadically in savanna and heath in northern W.A., N.T. and Qld and extends to New Guinea, Malesia and Burma. Flowers Dec.–July.