WATTLE

Acacias of Australia

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Acacia dimidiata Benth.

Family

Fabaceae

Distribution

Occurs in extreme north-western Qld and through tropical N.T.

Description

Slender resinous shrub or tree to 7.5 m high. Bark mottled grey; old bark brownish to dark grey, corrugated. Branchlets ±angular towards apices, yellowish, brown or grey-brown, squamulose, densely crisped-pubescent to tomentose, ribbed. Phyllodes obliquely ovate-rhomboidal, flat, (4–) 5.5–10 (–15.5) cm long, (16–) 20–80 (–95) mm wide (to 150 mm wide on young plants), rounded at base on upper side, tapering into pulvinus, with obtuse and mucronate apex, sparsely to moderately tomentulose-waxy especially between nerves, slightly vernicose, with 4 or 5 prominent nerves (sometimes with a few 3-nerved phyllodes) concurrent with lower margin near base (only the nerve closest to abaxial margin extending to mucro), with minor nerves reticulate; gland 1, prominent, basal. Spikes 2.5–7 cm long, golden. Flowers 5‑merous; calyx 0.8–1.4 mm long, dissected to ±1/2, with lobes slightly pubescent and with fimbriate margins; corolla 1.5–2.1 mm long, dissected to 1/2, glabrous; ovary densely tomentose. Pods ±straight, ±terete, 5.5–15.5 cm long, tapered towards base, crustaceous, densely puberulous, dehiscing from apex and curved back. Seeds longitudinal, oblong to narrowly oblong, 6–7.5 mm long, brownish black to black.

Phenology

Flowers July–Oct.

Habitat

Grows in open eucalypt woodland in sandy soil over laterite.

Specimens

N.T.: 5 km S of Fergusson R. on Stuart Hwy, M.D.Tindale 6019 & C.Dunlop (CANB, K, NSW, Z); on road to Jabiru, 2 km N of Pine Creek, T. & J.Whaite 7981 (A, AD, CANB, MEL, NSW). Qld: Corinda–Westmoreland Stns, C.H.Gittins 1292 (NSW).

Notes

Allied to A. humifusa which has spikes 1–5 cm long, silky-hairy corollas, ±tomentose phyllodes and bracteoles conspicuous before anthesis.

FOA Reference

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

Author

Dr M.D.Tindale and Dr P.G.Kodela with the assistance of M.Bedward, S.J.Davies, C.Herscovitch, D.A.Keith and/or D.A.Morrison

Minor edits by J.Rogers