Acacia rostellifera Benth.
Acacia rostellifera Benth.
Occurs in coastal areas of south-western W.A. from Shark Bay S to Cape Naturaliste and from Bremer Bay E to Israelite Bay. Naturalized near Barwon Heads, Vic. At the northern end of the range in W.A. it extends inland to Latham.
Dense shrub or tree to 6 m high, often clonal. Bark dark grey and fissured on main trunks. Branchlets glabrous, scurfy. Phyllodes linear to linear-elliptic or narrowly oblanceolate,4.5–11.5 cm long, 3–17 mm wide, l:w = 4–30, uncinate to subuncinate, sometimes excentrically rostellate, thin, frequently puncticulate, glabrous, 1-nerved or imperfectly 2‑nerved; lateral nerves obscure; glands not prominent, 4–13 mm above pulvinus, often also at base of mucro. Inflorescences 3–9-headed racemes; raceme axes 1–3 cm long; peduncles 3–8 (–10) mm long, glabrous; heads globular, 5–7 mm diam., to 10 mm when fresh, subdense, 15–25-flowered, golden. Flowers 5-merous; sepals united into a shallowly lobed or sinuate-toothed calyx. Pods ±erect, submoniliform, to 9 cm long, 5–7 (–8) mm wide, firmly crustaceous, breaking readily at constrictions. Seeds longitudinal, oblong to widely elliptic, 4–6 mm long, dull or shiny, dark brown; aril prominent, twice-folded, orange or red.
Grows in sand, frequently on dunes, where it may form monotypic stands.
W.A.: 24.2 km S of Billabong on North West Coastal Hwy, M.E.Ballingall 1896 (BRI, PERTH); 6 km inland of Point Malcolm, R.Hnatiuk 761133 (PERTH); 8 km S of Geraldton towards Perth, B.R.Maslin 75 (PERTH); near Fitzgerald R. crossing, Fitzgerald R. Natl Park, B.R.Maslin 3480 (PERTH); Cape Naturaliste Lighthouse, L.Nunn 544 (PERTH). Vic.: Barwon Heads, 11 Oct. 2004, B.Wood s.n. (MEL 2278502).
Information on the biological and ecological features, and the utilisation potential, of this species is given in B.R.Maslin and M.W.McDonald, AcaciaSearch: Evaluation of Acacia as a woody crop option for southern Australia, RIRDC Publication No. 03/017, 194–197 (2004).
A member of the ‘A. bivenosa group’. Although A. rostellifera is somewhat variable in phyllode shape and size (e.g. see A.R.Chapman & B.R.Maslin, Nuytsia 8: 250 (1992)) it is distinguished from its closest relatives by a combination of the following characters: branchlets scurfy, phyllodes thin, green, frequently puncticulate (i.e. possessing minute brown peltate glandular hairs which seem to leave obscure shallow depressions in the phyllode surface), 1-nerved or with a very faint second nerve, uncinate to subuncinate and with a distinct mucro. Specimens from around the Murchison R. have distinctly 1-nerved, narrow phyllodes (3–6 mm wide) and shorter racemes with consistently fewer flower-heads than normal. This variant extends to Shark Bay where it can be confused with A. ligulata. Also closely related to A. xanthina, with which it appears to hybridise near Jurien Bay. Narrow, green phyllode forms of A. blakelyi may resemble A. rostellifera, but are readily distinguished by their horizontally flattened phyllodes with the gland situated on the adaxial surface (not on the adaxial margin as in A. rostellifera).
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 & J.Rogers
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