Acacias of Australia

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Acacia horridula Meisn.




Occurs in south-western W.A. in the Darling Ra. from the Helena Valley S to the Serpentine R., and also recorded from the adjacent coastal plain at Maddington.


Shrub to c. 0.6 m high. Branchlets normally red-brown to light brown, puberulous with antrorse to ±patent hairs. Stipules setaceous to narrowly triangular, 2.5–4 mm long. Phyllodes often crowded, patent, narrowly semi-trullate with a prominent gland-angle on adaxial margin near base, 6–8 mm long, 1.5–2.5 mm wide, acuminate, pungent, with slender, c. 1 mm long cusp, rigid, green, glabrous; midrib prominent, central; lateral nerves absent. Inflorescences simple, 1 per axil; peduncles 5–10 mm long, puberulous; heads globular, 4-flowered, pale yellow. Flowers 4-merous; sepals united. Pods terete, narrowed at both ends, curved, to 7.5 cm long and 3.5 mm wide, red-brown, striate, subglabrous. Seeds longitudinal, oblong, 4–5 mm long; aril terminal, conical.


In the Darling Ra. it grows on rocky hillsides in Eucalyptus woodland.


W.A.: Serpentine, B.R.Maslin 4175 (PERTH); Maddington, 6 Aug. 1904, A.Morrison s.n. (K, PERTH); Helena Valley, end [of] Moola Rd, J.Seabrook 13 (PERTH).


The description of A. horridula in G.Bentham, Fl. Austral. 2: 350 (1864) is a mixture of A. horridula (Preiss 1151), A. pycnocephala (Preiss 965) and A. semitrullata (Drummond s.n. and Oldfield s.n.). These species together with A. hastulata, A. inops and A. uliginosa comprise the ‘A. horridula group’, fide B.R.Maslin, Nuytsia 2: 270 (1978). Acacia neorigida, A. phaeocalyx and A. plautella appear to have fairly close relationships to this group.

FOA Reference

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