Acacias of Australia

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Acacia olsenii Tindale




Occurs on the Southern Tablelands of N.S.W. from Minuma Ra. S to Mother Woila, Tabletop Mtn and Tuross R.


Tree 3–15 m high. Bark smooth, later sometimes slightly corrugated towards base, grey-green, dark grey, brown or black. Branchlets angled or vertically flattened towards apices, mostly glabrous, rarely minutely hairy along non-prominent ridges, pruinose. Young foliage-tips brownish green or cream-coloured. Leaves dark green; petiole above pulvinus 1.3–3.5 cm long, vertically flattened, glabrous or sometimes with sparse short white hairs, bluish glaucous, with 1 (rarely 2) prominent spherical usually glabrous gland(s) at or near base of lowest pair of pinnae, rarely absent; rachis 4.5–10 cm long, ±vertically flattened, usually with a spherical gland at base of all pairs of pinnae, often also with 1–4 smaller often contiguous interjugary glands between some pairs of pinnae; pinnae 9–17 pairs, 3.5–8.3 cm long; pinnules 50–106 pairs, ±oblong to cultrate, mostly 1–2.2 mm long and 0.4–0.5 mm wide, ciliolate otherwise glabrous, subacute. Inflorescences in axillary or terminal false-panicles; peduncles 2–6 mm long, glabrous. Heads 7–12-flowered, deep yellow. Pods usually slightly constricted between seeds, 2.5–12 cm long, 6–9 (–12) mm wide, thinly coriaceous, dark brown or blackish, bluish pruinose, glabrous; margin ±prominent.


Flowers May.


Often grows in stands usually within 50 m of creeks, on very steep, dry, rocky hillsides facing NW, at heads of gullies and tops of knife-edge ridges, in open forest, on scree, mostly on slate or shale, sometimes in alluvial sands.


N.S.W.: Mother Woila Mtn, 26 Apr. 1980, J.Benson (NSW); E of Big Badja Hill, M.D.Crisp 2377, D.J.Cummings & A.Tyrrel (CANB, NSW); NW face of Mother Woila Peak, F.Grossbechler CBG817372 (CANB, NSW); Mother Woila, I.Olsen 3094 (CANB, K, L, MEL, NSW, TL, UC, US, Z); Razorback ridge approach to Mother Woila, I.Olsen 3091 (AD, PERTH).


Acacia storyi is very closely allied to A. olsenii but differs in its heads cream-coloured or pale yellow and 14–20-flowered, often less numerous pairs of pinnules and margins of the pinnules with fewer white cilia. There is a considerable disjunction in the distribution of these two species, as A. olsenii occurs in south-eastern N.S.W., and A. storyi is endemic to Blackdown Tableland, Qld.

FOA Reference

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


M.D.Tindale, P.G.Kodela

Minor edits by B.R.Maslin & J.Reid