Acacia spinosissima Benth., Linnaea 26: 621 (1855)
Intricate, compact or spreading, glabrous shrub 0.2–1.5 m high. Branches substriate by ribs, pruinose, dividing into numerous, short, spreading, spinescent, commonly aphyllous branchlets. Phyllodes sometimes some subfasciculate on short branchlets, ascending to erect, narrowly oblong, straight or very shallowly sigmoid, usually 3–8 mm long, 1–2 mm wide, excentrically mucronulate, green; midrib obscure or slightly raised; lateral nerves absent. Inflorescences rudimentary 1-headed racemes with axes <0.5 mm long; peduncles 4–12 mm long; heads globular, usually 3–3.5 mm diam. and 8–18-flowered, bright lemon yellow; bracteoles absent or few. Flowers 5-merous; sepals united into a truncate calyx; petals nerveless. Pods prominently rounded over seeds on alternate sides, to 6 cm long, 3–5 mm wide, thinly coriaceous, pruinose. Seeds longitudinal, oblong, 2.5 mm long, dark brown, verruculose; aril clavate.
Scattered from Cadoux S to Brookton and E to near Lake King, south-western W.A. Grows in sand or sometimes clay loam.
Often resembling A. erinacea in its spinose branchlets and small phyllodes but A. erinacea has whitish scurfy phyllodes, bracteolate, more-flowered heads and very different pods and seeds. The absence of bracteoles is a possible link to A. rostellata . Sometimes confused with A. ulicina or A. jacksonioides .
Two variants are recognised and may ultimately be shown to warrant formal rank.
The typical variant is a compact shrub 0.2–0.4 m high; phyllodes 3–7 mm long, c. 1 mm wide; peduncles 4–6 mm long; heads 3–3.5 mm diam., 8–10-flowered; petals 1.5–1.7 mm long; pods 3–3.5 mm wide. It is known only by collections from near Brookton, Tammin, Wyalkatchem, Muntadgin, Bruce Rock and Holt Rock in south-western W.A. (representative collections: R.Cumming 1346 ; R.J.Hnatiuk 790150 ).
The robust variant is a spreading shrub 0.5–1.5 m high; phyllodes 4–8 mm long, rarely 15 mm long, 1–2 mm wide; peduncles 5–12 mm long; heads 4–6 mm diam., 10–18-flowered, rarely 23; petals 2–2.5 mm long; pods 4–5 mm wide; seeds not seen. It is known only from near Cadoux, Tammin, Boorabbin and Lake King in south-western W.A. (representative collections: M.A.Burgman 1331 & S.McNee and B.R. Maslin 139).
Type of accepted name
Swan R., W.A., J.Drummond (5th collection or supplement to 5th collection) 51; syn: K (herb. Hooker and herb. Bentham sheets); isosyn: OXF, P, PERTH, W; probable isosyn: NSW.
J.H.Maiden, J. & Proc. Roy. Soc. New South Wales 53: pl. 12, figs 17–22 (1920).
W.A.: Gairdner Reserve, S of Tammin, R.Cumming 1346 (PERTH); 17 km due NE of Brookton, R.J.Hnatiuk 790150 (PERTH); 42 km NE of Coujinup Hill, M.A.Burgman 1331 & S.McNee (CANB, PERTH); 1.6 km S of Cadoux towards Manmanning, B.R.Maslin 139 (PERTH).