Family

Fabaceae

Distribution

Occurs from near Hamelin Pool S to Cockleshell Gully and E to near Wubin, W.A., and not common in this range.

Description

Shrub or tree 2–4 m high, usually wispy or straggly. Branchlets often ±arching or pendulous, ±pruinose. Phyllodes often pendulous, linear to linear-elliptic, straight to curved, 10–20 cm long, 4–10 mm wide, tapering to pulvinus, acute to acuminate, coriaceous, grey-green to subglaucous, glabrous; nerves numerous, fine, subdistant, rarely anastomosing; midnerve most evident; marginal nerves yellow or yellowish, prominent; pulvinus 3–6 mm long. Inflorescences 1–4-headed racemes; raceme axes usually 2–8 mm long (rarely to 45 mm), pruinose, glabrous; peduncles 6–20 mm long, glabrous; spikes 12–23 mm long, 6–7.5 mm diam., golden. Flowers 5-merous; sepals united, puberulous. Pods linear, slightly raised over seeds, curved, c. 7 cm long and 5–6 mm wide, coriaceous, pruinose, glabrous. Seeds longitudinal, subdiscoid, compressed, 4–4.5 mm long, glossy, dark brown; pleurogram shortly U-shaped or nearly semicircular; funicle-aril short, thick.

Habitat

Grows in yellow sand and sandy loam on sandplains and flats in heath, scrub and shrubland.

Specimens

W.A.: near Hamelin Pool, J.S.Beard 3028 (PERTH); 9.1 km on road from Kalbarri to Ajana, R.S. & R.A.Cowan A807 (CANB, K, NY, PERTH, US); 0.3 km N of Wubin on Wubin–Mullewa rd, N.Hoyle 332 (MEL, PERTH); 19.2 km N of Cockleshell Gully, W.A.Loneragan 67.032 (PERTH); 6.5 km N of Coorow, Geraldton Hwy, B.R.Maslin 4335 (PERTH).

Notes

Although the racemes are commonly 2–8 mm long, much longer ones (to 4.5 cm), are found occasionally (e.g., 12.8 km SW of Winchester, 1 Sept. 1974, C.Chapman, PERTH); examples of several racemes per axil are also found occasionally (e.g. from Witcherina, G.Phillips for A.M.Ashby 4838, NY, PERTH). Data on habit are limited, but a wispy or straggly form from the Murchison R. area is often noted; there are other collections that omit such detail and a very few which note the plant as a compact shrub (e.g. 5 km S of Winchester, Sept. 1974, C.Chapman, PERTH, and from near the mouth of the Murchison R., J.S.Beard 2035, PERTH).

Formerly confused with A. yorkrakinensis subsp. acrita which differs largely in its regularly densely branching habit, by its somewhat shorter pulvinus with red or brown phyllode margins and by its oblong-elliptic seeds with a conspicuous funicle-aril and elongate U-shaped pleurogram. There may also be a difference in phyllode colour, but the paucity of observations of this characteristic, as well as of habit and fruits, makes assessment of the taxa extremely difficult; future studies may suggest they be combined, each with infraspecific rank. Acacia yorkrakinensis extends SE from the Perenjori-Wubin area which is the southern end of the range of A. signata.

FOA Reference

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

Author

B.R.Maslin, R.S.Cowan