Acacia robiniae Maslin
Acacia robiniae Maslin
Restricted to the Albany–Mt Manypeaks area with a disjunct occurrence at Mt Arid, south-west W.A.
Spreading, open shrub to 0.6 m high. Branchlets sparsely to moderately shortly pilose and/or antrorsely puberulous. Stipules 1.5–2.5 mm long, persistent bases ±pungent. Phyllodes inequilateral, obdeltate to shallowly obtriangular with a prominent gland-bearing angle on adaxial margin, with adaxial proximal margin convex and ±contiguous with branchlet and adaxial distal margin concave, 3–8 mm long, 3–8 mm wide, pungent, glabrous; midrib near abaxial margin. Inflorescences simple, 1 per axil; peduncles 1–3 mm long, glabrous or subglabrous; heads globular, 2-flowered, ±white; buds attenuate. Flowers 4-merous; sepals 1/2–2/3-united, with lobes broadly triangular; petals narrowed and prominently 1-nerved at apices. Pods narrowly oblong, shallowly curved, to 6 cm long, 3–4 mm wide, coriaceous-crustaceous, glabrous; margins thick. Seeds longitudinal, oblong, 2.5–3 mm long, glossy, dark brown; aril terminal.
Grows in sand over laterite in Jarrah (Eucalyptus marginata) woodland, in seasonal swamps and, at Mt Manypeaks and Mt Arid, in loam over granite.
W.A.: Mt Arid, G.J.Keighery 7645 (PERTH); Marbellup, c. 15 km W of Albany, B.R.Maslin 3781 & 3781A (MEL, NY, PERTH); Lower Kalgan R., R.D.Royce 3725 (NSW, PERTH).
A member of the ‘A. biflora group’ resembling A. divergens in phyllodes but readily distinguished by 2-flowered heads. Both A. robiniae and A. biflora occur around Albany and, as noted by B.R.Maslin, Nuytsia 2: 295 (1978), it is probable that Robert Brown had in mind both species when describing A. biflora. Acacia biflora is distinguished by its ±obscurely 3–7-nerved petals, abruptly acute flower buds (narrowly ovoid to ±cylindrical in A. robiniae) and phyllodes with a minor nerve extending from the pulvinus towards the gland; see B.R.Maslin, Nuytsia 2: 291 (1978), for additional distinguishing features. Specimens from the Fitzgerald R. Natl Park combine phyllodes of A. biflora with flowers of A. robiniae.
Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia
Minor edits by B.R.Maslin
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