Acacia helmsiana Maiden
WATTLE
Acacias of Australia
Family
Fabaceae
Distribution
Occurs in the arid zone from near Wiluna, W.A., to near Mt Olga, N.T., and in far western S.A.
Description
Glabrous shrub to 2 m high; inflorescences and young growth resinous. Phyllodes sigmoid to shallowly incurved, sometimes straight, terete to subterete, rarely flat in N.T., 0.5–2 cm long, 0.5–1 (–1.5) mm wide, rounded-truncate, rostriform with an excentric blunt point, uncinate to subuncinate, dark green, very obscurely 2-nerved, 1-nerved per face when flat; nerves commonly brownish and slightly impressed when dry; gland at base of mucro. Inflorescences simple, 1 per axil; peduncles 5–15 mm long, ebracteate at base; heads globular, 20–30-flowered, light- to mid-golden. Flowers 5-merous; sepals to 1/2-united. Pods (immature) constricted between seeds, strongly curved to 1½-coiled, to 4 cm long, 4 mm wide, longitudinally reticulate. Seeds (immature) longitudinal.
Habitat
Grows on sand plains or dunes, often with spinifex.
Specimens
W.A.: 1.6 km N of No. 11 Well, Canning Stock Route, Aug. 1964, W.H.Butler et al. (PERTH); Queen Victoria Spring Nature Reserve, D.J.Pearson 222 (PERTH). N.T.: 35 km WSW of Mt Olga, P.K.Latz 5732 (NSW, PERTH). S.A.: 1.5 km E of Vokes corner on road to Emu Junction, N.N.Donner 7334 (NSW).
Notes
Some specimens from N.T. are unusual in having flat phyllodes 7–13 mm long.
Because of its presumed relationship to A. abrupta this species is referred to the ‘A. wilhelmiana group’. However, its non-racemose, ebracteate peduncles suggest close affinities to the ‘A. johnsonii group’. Acacia abrupta has longer, obscurely 4-nerved phyllodes with a basal gland and either bracteate peduncles in racemes or non-racemose, ebracteate peduncles. As these are both arid zone resinous shrubs with globular flower-heads and relatively short phyllodes, they are easily confused.
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
B.R.Maslin
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