Family

Fabaceae

Distribution

Occurs in the Kimberley region of northern W.A., at the Prince Regent R. and E of Walcott Inlet (where it is seemingly uncommon) and the Drysdale R. area (where it is common).

Description

Shrub to 4 m high, sometimes a tree to 6 m high, openly branched, ±obconic, glabrous, variably resinous. Branchlets rather prominently ribbed, angled towards apices, variably tuberculate. Phyllodes asymmetrically narrowly elliptic, straight but sometimes shallowly recurved at apices, mostly 4–7 cm long, 6–16 mm wide, commonly ±acute, mucronate, thin, often drying brownish, sparsely tuberculate, with numerous subdistant nerves; nerves 3–5, slightly more pronounced than the intervening venules; anastomoses few or absent; glands 2 or 3, not prominent, with lowermost 0–1 mm above pulvinus and uppermost at base of mucro. Inflorescences simple, 2 per axil; spikes 1.5–4.5 cm long, narrow, golden; peduncles 1.5–3 mm long. Flowers 5-merous; sepals free. Pods narrowly oblong, narrowed at base, to 7.5 cm long, 6–8 mm wide, woody, red-brown, finely obliquely nerved, dehiscing elastically from apex; margins narrowly winged with wing c. 2 mm wide. Seeds oblique, elliptic, 4–4.5 mm long, somewhat shiny, brown; funicle/aril narrowly turbinate.

Habitat

Grows most commonly on sandstone in Eucalyptus woodland.

Specimens

W.A.: Drysdale R. Natl Park, S.J.Forbes 2322 (BRI, MEL, PERTH); Blyxa Ck, Prince Regent R. Reserve [Natl Park], A.S.George 12492 (BRI, PERTH); 2 km E of junction of Charnley & Calder Rivers, A.V.Milewski 224 (PERTH).

Notes

A variant of uncertain rank is known from a single collection from the Prince Regent R. area, viz. 15 km E of King Cascade, K.F.Kenneally 10537 & B.P.M.Hyland (PERTH). This specimen resembles A. tenuispica in phyllode shape and size and short peduncles, but has the distinctive 2-nerved, reticulately nerved phyllodes and resin-ribbed branchlets of A. richardsii. Although these characters suggest that the specimen represents a hybrid, A. richardsii is not known to occur in the Prince Regent R. area and A. tenuispica is apparently uncommon there.

The carpological characters, narrow spikes and free sepals relate A. tenuispica to A. richardsii (which has shorter, mostly 2-nerved, reticulately nerved phyllodes), A. conjunctifolia (which has shorter, clustered phyllodes) and A. gonocarpa (which has narrower, linear phyllodes and prominently winged pods). Acacia lentiginea and A. kimberleyensis seem to be related to this group, as does the ‘Minni Ritchi’ species, A. delibrata.

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