Acacias of Australia

Print Fact Sheet

Acacia trigonophylla Meisn.




Scattered from Three Springs S to Rocky Gully and Hyden area, with one early collection (type of A. pteroclada) presumably from Geraldton, south-western W.A.


Erect much-branched glabrous shrub 1–2.5 m high. Branchlets angled, green, with margins normally scabridulous. Stipules normally caducous, inconspicuous. Phyllodes continuous with branchlets, trifariously decurrent and forming narrow wings 1–2 mm wide; free portion of phyllodes patent to inclined, linear to linear-lanceolate, narrowed towards the apex, straight to shallowly recurved, sometimes shallowly incurved, 1–4 (–6) cm long, 1–3 mm wide, coarsely to sharply pungent, subrigid, 5-nerved; midrib prominent; upper margin flat, 0.5–1 mm wide and 2-nerved; gland not prominent, to c. 1 cm above base. Inflorescences simple, 1 or 2 per axil; peduncles 5–15 mm long; heads globular, 28–32-flowered, golden. Flowers 5-merous; sepals united. Pods submoniliform, ±straight, to 8 cm long, 4–6 mm wide, thinly coriaceous-crustaceous. Seeds longitudinal, ±oblong, 4–5 mm long; aril facing base of pod.


W.A.: 9.7 km W of Three Springs, J.S.Beard 7253 (PERTH); 14.5 km S of Dumbleyung towards Katanning, B.R.Maslin 650 (MEL, PERTH); The Humps, 17 km due NNE of Hyden, B.R.Maslin 6151 (AD, MEL, PERTH); Billyacatting Hill Reserve, 11 km NE of Kununoppin, B.G.Muir 114(5.2) (PERTH).


G.Bentham, Fl. Austral. 2: 322 (1864), erroneously gave the number of flowers as 40–50 per head; also, the sepals are united, splitting only upon dissection.

Plants with longest phyllodes occur near Three Springs. Specimens with short phyllodes can be confused with A. incurva or some forms of A. daviesioides.

This is one of only a few species of Acacia where the aril faces the base, rather than the apex of the pod. Seeds of A. dentifera show the same arrangement.

FOA Reference

Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia