Acacia wilsonii

General Plant Info

Acacia wilsonii is a low, wiry shrub, 0.2-0.3 m high, endemic to Western Australia. It grows on white/yellow sand & lateritic gravel, sandy clay over laterite.

Relationships not clear but perhaps has some affinities with Acacia ridleyana ; both species have free sepals and variably united petals, linear, acuminate bracteoles and linear, terete or subterete pods. However, Acacia ridleyana has pulvinate, flat, much shorter phyllodes with clear articulation between pulvinus and branchlet. Phyllodes that are epulvinate and continuous on the branchlets are not common in section Plurinerves. Both Acacia campylophylla and Acacia chapmanii , in this section, have such phyllodes, but they are much shorter than those of Acacia wilsonii and furthermore, their petals and sepals are free and they have very different pods.

Geographic distribution

Beard’s Provinces: South-West Province.

IBRA Regions: Geraldton Sandplains.

IBRA Subregions: Lesueur Sandplain.

Local Government Areas (LGAs): Carnamah, Coorow, Dandaragan.

Identification

Prostrate shrub normally 0.2–0.3 m high. Branchlets at first slightly angled, villous to pubescent with minute black resin-hairs intermixed, soon terete and glabrous except for resin-hairs.

Phyllodes continuous on branchlets, ascending to erect, shallowly curved to shallowly sigmoid or sinuous, terete, 6.5–22.5 cm long, 1–1.5 mm diam., with curved-acute and innocuous apex, coriaceous to semirigid, glabrous, with 8 distant, strongly raised nerves.

Inflorescences simple, 1 (2) per axil; peduncles 4–10 mm long, to 14 mm long in fruit, villous and with minute resin-hairs intermixed; heads globular, 8 mm diam., 24–37-flowered, golden. Flowers 5-merous; sepals 1/2–3/4-united.

Pods linear, not constricted between seeds, slightly curved, subterete, to 5.5 cm long, 3–3.5 mm wide, thinly crustaceous, dotted with minute, black resin-hairs.

Seeds longitudinal, oblong, 2–3 mm long, dull brown, tuberculate, the tubercles irregular-shaped; aril apical, yellow.

Links

http://www.worldwidewattle.com/speciesgallery/wilsonii.php?id=14154

http://www.anbg.gov.au/abrs/online-resources/flora/stddisplay.xsql?pnid=41497