Acacia helmsiana Maiden, J. & Proc. Roy. Soc. New South Wales 53: 174; pl. 10, figs 18–22 (1920)
Glabrous shrub to 2m 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 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, the base ebracteate; 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 1-coiled, to 4 cm long, 4 mm wide, longitudinally reticulate. Seeds (immature) longitudinal.
Occurs in the Arid Zone from near Wiluna, W.A., to near Mt Olga, N.T., and in far western S.A. Grows on sand plains or dunes, often with spinifex.
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.
Type of accepted name
Victoria Desert Camp 42 [c. 27S and 127E], W.A., 6 Sept. 1891, R.Helms s.n .; holo: NSW; iso: K, PERTH.
J.H.Maiden, loc. cit. ; B.R.Maslin, in J.P.Jessop (ed.), Fl. Central Australia 119, fig. 158E (1981); D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 53 (1992).
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).