Acacia trigonophylla Meisn., in J.G.C.Lehmann, Pl. Preiss . 2: 199 (1848)
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.
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.
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.
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.
Type of accepted name
Swan R., W.A., J.Drummond 2: 144; syn: BM, CGE, E, G, G-DC, LD, MEL, NSW (dated 1844), P, PERTH, W; see B.R.Maslin & R.S.Cowan, Nuytsia 9: 413 (1994), for note on types.
Acacia pteroclada F.Muell., Fragm . 4: 3 (1863). Type: Champion Bay [Geraldton], W.A., ‘...grows in dense York Gum thickets from ironstone gravelly soil’, P.Walcott ; holo: MEL; iso: PERTH (Fragment ex MEL).
W.R.Elliot & D.L.Jones, Encycl. Austral. Pl. 2: 123 (1982); M.Simmons, Acacias Australia 2: 15 (1988).
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).