Acacias of Australia

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Acacia semitrullata Maslin




Occurs from Yarloop S to Collie and the Whicher Ra., south-western W.A.


Erect shrub 0.3–0.5 m high, sometimes taller. Branches orange-brown. Branchlets antrorsely puberulous, with hairs often appressed. Stipules narrowly triangular, sometimes setaceous, 1–2 mm long, spreading, often incurved. Phyllodes patent, sometimes reflexed, narrowly semi-trullate with a slight gland-angle on adaxial margin near base, sometimes triangular-lanceolate without gland-angle, 5–10 mm long, 1.3–2 mm wide, pungent with a slender 0.5–1.5 mm long cusp, rigid, green, glabrous or subglabrous; midrib prominent; lateral nerves absent. Inflorescences simple, 1 per axil; peduncles 3–8 mm long, densely puberulous with straight patent hairs; heads globular, 5–8-flowered, cream to white. Flowers 4-merous; sepals c. 1/2-united, with lobes triangular; petals puberulous, 1-nerved. Pods terete, narrowed at both ends, to 7.5 cm long, 2–3 mm diam., red-brown, striate, finely appressed-puberulous. Seeds ±oblong, 4 mm long; aril terminal, conical.


Grows in sand in open heath, frequently fringing seasonally dry swamps, and in sand over laterite in shallow depressions in open Jarrah (Eucalyptus marginata) forest.


W.A.: W of Yarloop, R.J.Cranfield 121 (NSW, PERTH); Whicher Ra., A.S.George 6212 (NSW, NY, PERTH); 3.2 km SW of Donnybrook towards Capel, B.R.Maslin 448 (NSW, NY, PERTH).


A member of the ‘A. horridula group’, most closely related to A. uliginosa which has sparser branchlet hairs restricted to the ribs, erect stipules, 8–15-flowered heads, and glabrous, nerveless petals.

FOA Reference

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