Acacias of Australia

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Acacia tetragonocarpa Meisn.




Discontinuous, occurring in the Perth–Jarrahdale, Busselton–Witchcliffe and Albany areas, south-western W.A.


Straggly rush-like ±glabrous shrub 0.4–1 m high, sometimes prostrate or semi-prostrate. Branches slender and wiry, terete, finely striate with yellow ribs, green and ±sulcate between ribs. Phyllodes reduced to continuous thin horizontally flattened narrowly triangular scales, 1.5–3 mm long; bipinnate leaves sometimes persistent at base of stems. Inflorescences simple, 1–3 in axil of scales; peduncles 7–15 mm long, slender; heads 1–4-flowered, commonly 2-flowered, yellow; bracteoles persistent, navicular, c. 1 mm long; buds cylindrical to narrowly obovate, 1 mm wide. Flowers 4-merous; sepals united, c. 1/3 length of corolla; petals finely flabellate-striate. Pods stipitate, shallowly curved, 2–6 cm long, 4–5 mm wide, acute to acuminate, thinly coriaceous-crustaceous, acutely quadrangular by flat winged margins 1–2 mm wide, reddish brown, glabrous. Seeds longitudinal, oblong, 5 mm long; aril terminal, conical.


Grows in swampy and seasonally wet sandy soil in Paperbark (Melaleuca sp.) or Jarrah (Eucalyptus marginata) woodland, with one hillside collection from regenerating heath in sandy loam over laterite.


W.A.: c. 6 km from Sullivan Rock towards Jarrahdale, R.J.Cumming 1089 (PERTH); Bateman, SE of Perth, A.S.George 9865 (CANB, K, MEL, NSW, NY, PERTH); West Cape Howe Natl Park, N.Gibson & M.Lyons 136 (PERTH); c. 2 km NE of Witchcliffe, S.D.Hopper 4393 (PERTH).


Distinguished from the more northerly distributed A. cummingiana which has 8–12-flowered heads, pods 8–10 mm wide and seeds presumably oblique; see B.R.Maslin, Nuytsia 10: 175 (1995), for further details.

G.Bentham, Fl. Austral. 2: 336 (1864), appears to have included elements of A. aemula in his description of A. tetragonocarpa.

FOA Reference

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