Family

Fabaceae

Distribution

Restricted to the headwaters of the South and East Alligator Rivers, Kakadu Natl Park, N.T.

Description

Shrub to 6 m tall, erect, spindly, sometimes flowering when less than 1 m. Branchlets angular, glabrous, slightly resinous. Phyllodes linear, 11–17.5 cm long, 1–1.5 mm wide, acute with a deciduous callus point, rather thick, glabrous; one longitudinal nerve forming a midrib, with 4–6 less prominent non-anastomosing nerves on each side of it; gland basal, inconspicuous; pulvinus 1.5–3 mm long. Spikes single at base of rudimentary axillary shoot, 15–20 mm long, rather open, yellow; peduncles 2–6 mm long, resinous. Flowers 5-merous; calyx broadly cupular, 0.4–0.6 mm long, lobed to middle, somewhat resinous, sometimes with a few marginal hairs; corolla 0.8–1.1 mm long, lobed to middle, glabrous; ovary glabrous, resinous. Pods straight, linear, acute, to 6.5 cm long, 2–2.5 mm wide at widest part, 1.5 mm wide at isthmuses, glabrous, slightly resinous; valves rather thick with raised reticulate nerves, constricted between seeds and raised over them. Seeds longitudinal, obloid, c. 2.6 mm long, 1.6 mm wide; aril pale yellow, folded twice beneath seed.

Phenology

Flowers collected Feb. & July; fruits collected Feb.

Habitat

Occurs on gentle slopes in sandy soil and in crevices in sandstone pavements where it is often common.

Specimens

N.T.: 5 km E of Jim Jim Falls, N.B.Byrnes 2724 (BRI, DNA, K); Deaf Adder Gorge, R.E.Fox 2519 (BRI, DNA).

Notes

Acacia proiantha is not closely related to any other species of Acacia sect. Juliflorae. It has long narrow phyllodes with one nerve more prominent than the rest, forming a distinct midrib; its flowers are small with petals only about 1 mm long; and its pods are somewhat moniliform with small longitudinal seeds.

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 B.R.Maslin

L.Pedley