Common Name

Witarra

Family

Fabaceae

Distribution

Restricted to the Pilbara region in north-western W.A. where known from disjunct populations in the Hamersley, Hancock and Ophthalmia ranges.

Description

Erect, spindly, wispy, single-stemmed shrub 2.5–3.5 m high, stems c. 1.5 cm diam., upper branches scarred where phyllodes have fallen. Branchlets lenticellular, glabrous, resinous. Stipules persistent, 0.7–1.5 mm long, erect, often enveloped by resin. Phyllodes asymmetrically oblong to oblong-elliptic, lower margin ±straight, upper margin often shallowly convex, sub-crowded, wide-spreading, 2–3 (–5) mm long, 1.2–1.8 mm wide, l: w = 1–2.3, abruptly terminated at the rounded apices by a short (0.3–0.5 mm long) but distinct, excentric, pungent cusp, glabrous; midrib not prominent, often with a less pronounced second nerve; pulvinus very indistinct; gland single, near or below centre of upper margin. Inflorescences simple, 1 per axil; peduncles 6–8 mm long, glabrous, dark red (fresh), base ebracteate; heads globular, densely 40–50- flowered, golden. Flowers 5-merous; sepals free. Pods narrowly oblong, flat but rounded over seeds, 20–40 mm long, 3–4 mm wide, firmly chartaceous, glabrous, stipitate. Seeds longitudinal, elliptic, c. 3 mm long, black but mottled pale yellow; funicle filiform, exarillate.

Phenology

Flowers July–Aug.

Habitat

Grows on calcareous rises adjacent to drainage lines with Eucalyptus, Melaleuca and Petalostylis over spinifex.

Specimens

W.A.: Hamersley Ra. [precise localities withheld for conservation reasons], N.E.Casson & E.M.Mattiske MCPL 1060 (PERTH), B.R.Maslin 8552 (K, MEL, PERTH), B.R.Maslin 8699 (MEL, PERTH) and E.Thoma 1153 (NSW, PERTH).

Notes

Related to and superficially resembles A. minutissima which differs in its growth form and slightly smaller and differently shaped phyllodes. Both species are related to A. maitlandii which has longer phyllodes.

FOA Reference

Flora of Australia Project

Author

J.Reid, B.R.Maslin