Acacia dorsenna Maslin
Acacia dorsenna Maslin
Fabaceae
Known only from two populations in a restricted area N of Norseman, W.A.
Dense domed glabrous shrub to c. 1.5 m high. Phyllodes inequilaterally elliptic to obovate, with markedly convex adaxial margin, 10–15 mm long, 5–9 mm wide, rounded-mucronulate with a ±lateral mucro, subfleshy, smooth, subglaucous, ageing dull green; midrib and lateral nerves absent or obscure; marginal nerves brownish; gland small, 0.5–2 mm above pulvinus. Inflorescences 7–10-headed racemes; raceme axes 1–2.5 cm long, enclosed when young by small bracts, often growing out with subsequent peduncles subtended by secondary phyllodes; peduncles 4–16 mm long, slender; heads globular, 15–21-flowered, bright mid-golden; bracteoles absent. Flowers 5-merous; sepals free. Pods (slightly immature) narrowly oblong, conspicuously rounded over seeds alternately on each side along the midline, to 6 cm long, 8–12 mm wide, firmly chartaceous, brown. Seeds (slightly immature) transverse, oblong-elliptic, to 4 mm long, scarcely arillate.
Grows in rocky red-brown sandy loam or clayey loam.
W.A.: c. 697 km from Perth on Norseman–Coolgardie road, E.M.Canning WA/68 2652 and 2662 (PERTH); near Norseman, c. 5 km along road to Kalgoorlie, B.Maloney 1/69 (PERTH); c. 25 km N of Norseman, D.J.E.Whibley 5455 (PERTH).
A member of the ‘A. prainii group’ and superficially might be mistaken for a large phyllode form of A. camptoclada, a species characterised by smaller, pungent phyllodes with the gland well above the pulvinus, shorter racemes and smaller, once- or twice-coiled pods. It resembles some forms of A. merrallii in phyllode shape and size but differs markedly in carpological features, its longer racemes and non-pungent phyllode.
Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia
B.R.Maslin
Minor edits by J.Rogers
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