Family

Fabaceae

Distribution

Restricted to the west Kimberley region of northern W.A., where it ranges from the Buccaneer Archipelago SE through the King Leopold Ra.

Description

Shrub or tree to 4 m high. Bark ‘Minni Ritchi’, dark red. Branchlets angular; ridges scarcely pubescent. Phyllodes linear, slightly tapering towards base, curved, 3.5–6.5 (–9) cm long, (0.5) 1–2 (–4) mm wide, apices terminated by a sub-setose point, thin-textured and not rigid, with yellowish appressed hairs, indistinctly multinerved with central nerve the most prominent; lenticels prominent; gland 0.4–3 mm above pulvinus. Spikes 2–4 cm long, dense, bright yellow, flowers sub-densely arranged. Flowers 5‑merous; calyx very reduced, less than ¼ length of corolla, gamosepalous, dissected to c. 1/2, fimbriolate; corolla c. 1.5 mm long, dissected to c. 1/2, glabrous. Pods linear, constricted between and rounded over seeds, 4–9 cm long, greenish brown, obscurely reticulate, villous especially when young, viscid. Seeds longitudinal, oblong-elliptic, compressed, brown to black; areole small, dark, surrounded by a closed pleurogram and wide, pale halo.

Phenology

Flowers May–July.

Habitat

Grows in savannah grasslands or on steep rocky slopes, often amongst quartzite.

Specimens

W.A.: Mt Bell, King Leopold Ra., E.M.Bennett 1881 (NSW, PERTH); Isdell Gorge in Isdell Ra., W Kimberley, D.Fell 276 (NSW, PERTH); Lachlan Is., Buccaneer Archipelago, W Kimberley Coast, K.F.Kenneally 8316 (NSW, PERTH); Inglis Gap, I.V.Newman 638 (NSW); Inglis Gap, T.Willing 86 (NSW, PERTH).

Notes

This is one of a small number of Acacia species with ‘Minni Ritchi’ bark. It is closely related to A. trachycarpa and A. cyclocarpa.

The name A. gracillima Saporta was described for a fossil-species, fide I.M.Turner (l.c.). A distinctive entity with extremely fine phyllodes (0.5–1 mm wide) and pendulous branchlets and known only from three locations in Prince Regent Natl Park (e.g. R.L.Barrett & M.D. Barrett RLB 3761, PERTH) is currently ascribed to A. gracillima but requires further; see B.R.Maslin, M.D.Barrett & R.L.Barrett, Nuytsia 23: 558–559 (2013) for discussion. Other variation within A. minniritchi appears not to be taxonomically significant, including occasional specimens with atypically wide phyllodes, e.g. (PERTH) from Cone Bay with atypically wide phyllodes (3–4 mm).

FOA Reference

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

Author

Minor edits by J.Rogers

Dr M.D.Tindale and Dr P.G.Kodela with the assistance of M.Bedward, S.J.Davies, C.Herscovitch, D.A.Keith and/or D.A.Morrison