Acacias of Australia

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Acacia semirigida Maiden & Blakely

Common Name

Stony Ridge Wattle




Occurs sporadically in south-eastern Qld from Goombungee and Kogan to near Eidsvold. The Stannary Hills locality given on the T.L.Bancroft paratype is evidently an error for Eidsvold. L.Pedley, Austrobaileya 1: 292 (1980), reported the species from the Blackdown Tableland but these plants appear not to be A. semirigida (see note below).


Shrub or tree to c. 4 m tall. Branchlets angled at extremities, dark reddish, glabrous. Phyllodes commonly ascending to erect, narrowly oblanceolate to narrowly elliptic or almost linear, straight to shallowly incurved, 4–9 cm long, 4–9 mm wide, thin to moderately coriaceous, glabrous, with distinct midrib and marginal nerves; lateral nerves absent or few and obscure; glands prominent and normally exserted, usually 2 or 3, with lowermost 5–20 mm above pulvinus. Inflorescences racemose; raceme axes 2–5 cm long, glabrous; peduncles 2–6 mm long, glabrous; heads globular, small, 15–25-flowered, pale yellow; bracteole laminae subcircular. Flowers 5-merous; sepals united. Pods straight-edged or slightly constricted between seeds, to 12 cm long, 8–11 mm wide, thinly coriaceous, dark brown or reddish brown, glabrous, slightly shiny. Seeds longitudinal, narrowly oblong to slightly elliptic, 7–8 mm long, slightly shiny, black, minutely pitted; aril clavate.


Grows usually on shallow soil over sandstone in open forest.


Qld: Barakula State Forest, N of Chinchilla, M.E.Ballingall 2201 (PERTH); 25 km ENE of Eidsvold, L.Pedley 4015 (BRI); Goombungee, near rubbish dump, G.Ward 198 (BRI).


Flowering and sterile specimens from the Blackdown Tableland differ from those further south in having only a single phyllode gland (e.g. K.A.Williams 85029, BRI). Further information is needed in order to ascertain the status of this entity.

Perhaps most closely related to A. everistii which has broader, uniglandular phyllodes. Sometimes resembles A. amoena and some forms of A. rubida both of which have narrower pods, and seeds with long, encircling funicles.

FOA Reference

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



Minor edits by J.Rogers