Botanical name

Acacia sabulosa Maslin, Nuytsia 12(3): 393 (1999)

Description

Glabrous, resinous (but not sticky), spreading, more or less 'v'-shaped shrubs (or sometimes small trees) 1-3 (-5) m tall and up to 3 m across, several-stemmed at or near base, rarely single-stemmed and branching at 1 m or more above ground level. Bark dark grey, smooth, becoming fissured at base of main stems with age. Branchlets rather slender, yellow to light brown or reddish brown. New shoots bright green. Phyllodes usually linear, (4-) 6-10 cm long and 1-3.5 mm wide, thin-textured, soft and flexible, ąstraight, dull green but sometimes scurfy (especially over nerves) giving phyllodes a bluish appearance; midrib not prominent, the minor nerves few, obscure (commonly not visible on narrowest phyllodes) and openly longitudinally anastomosing with some ąparallel to midrib; apex with a small blunt mucro. Glands (observe at x10 magnification or higher), situated on upper margin of phyllode 1-2 (-5) mm above the pulvinus, a smaller gland also at apex of phyllode at base of the mucro. Inflorescences simple, initiated synchronously with phyllodes on terminal and axillary new shoots, the subtending phyllodes mature or semi-mature by the time heads reach anthesis, the shoot seemingly continuing to grow after inflorescence production has ceased; peduncles quite long (6-20 mm) and slender; flower heads showy and fragrant at anthesis, globular, bright light golden, densely 35-50-flowered. Flowers 5-merous; sepals ž-5/6-united. Pods narrowly oblong, flat, raised over seeds alternately on each side, rarely constricted between seeds, to 6 cm long, about 10 mm wide, papery, transversely reticulate, yellow-brown to light brown, basal stipe slender and about 5 mm long. Seeds transverse to slightly oblique in the pods, obloid to ellipsoid, 4-4.5 mm long, brown, sub- shiny; funicle and aril membranous and creamy white.

Characteristic features

Glabrous, resinous, more or less 'v'-shaped shrubs (or sometimes small trees), normally multi-stemmed. Phyllodes usually long and narrowly linear (mostly 6-10 cm x 1-3.5 mm), thin-textured, ąstraight, dull green but sometimes scurfy (especially over nerves) giving phyllodes a bluish appearance, 1-nerved but midrib not prominent; gland at base of blunt apical mucro. Inflorescences simple, initiated synchronously with phyllodes on new shoots; peduncles quite long (6-20 mm) and slender; flower heads showy and globular. Pods narrowly oblong, flat, raised over seeds alternately on each side, broad (about 10 mm wide), papery, transversely reticulate, yellow-brown to light brown. Seed funicle and aril membranous and creamy white.

Distribution and ecology

This species has a discontinuous distribution. In northwest Western Australia it occurs in coastal and near coastal areas of the Pilbara between Port Hedland and Cossack, then further inland from between Marble Bar and Port Hedland and also from near Shay Gap; outside the Pilbara it occurs at Mandora (about 250 km due northeast of Port Hedland), the south-central Great Sandy Desert and the Little Sandy Desert. It also occurs in N.T. from near Sangster Bore (Tanami Desert). Although A. sabulosa is not common in the Pilbara it is normally abundant in places where it occurs, e.g. in the vicinity of Wickham and between Karratha and Port Hedland. Typically grows on deep red or brown pindan sand, commonly on sand dunes and associated with Soft Spinifex (Triodia pungens and T. epactia). However, near Shay Gap there is an atypical occurrence in skeletal soil on steep rocky slopes of hills.

Flowering and fruiting period

Flowers from May to July and pods with mature seeds occur in October and November.

Variation

A few specimens have atypically short/broad, narrowly oblong phyllodes, 5-7 cm long and 5-6 mm wide (e.g. on some plants from Telfer Mining Centre - the typical form of the species also grows in this same region).

Taxonomy

Acacia sabulosa was described by Craig (1983), under the name "A. sp.", as a component of the Pilbara coastal flora.

Affinities

Closely related to A. dictyophleba and A. melleodora (both of which occur in the Pilbara region) but readily distinguished from both by its usually long, narrowly linear, 1-nerved phyllodes. Also related to A. jensenii and superficially similar to A. hockingsii (neither of which occur in the Pilbara). See Maslin (1999) for discussion of affinities.

Conservation status

Not considered rare or endangered.

Origin of name

The botanical name is derived from the Latin sabulosus (sandy), in reference to the soil type in which the species grows.

References

Craig, G.F. (1983). Pilbara coastal flora. pp. 103. (Western Australian Department of Agriculture: Perth.)

Maslin, B.R. (1999). Acacia miscellany 16. The taxonomy of fifty-five species of Acacia, primarily Western Australian, in section Phyllodineae (Leguminosae: Mimosoideae). Nuytsia 12(3): 311-411.