Family

Fabaceae

Distribution

Occurs from the Wimmera region (western Vic.) to Yalata, NW of the Eyre Peninsula, S.A.

Description

Dense, round, spreading shrub 1–3 m high. Branchlets sparsely to densely puberulous, the hairs short or long, straight to slightly curved and closely appressed (or sometimes subappressed). New shoots commonly pale yellow, but varying from white to golden. Phyllodes often obovate to oblanceolate but range from oblong to oblong-elliptic, (1–) 1.5–3 (–3.5) cm long, 5–10 (–14) mm wide, rounded to obtuse-mucronate, grey-green to glaucous, with indumentum similar to branchlets, rarely ±glabrous, 1-nerved per face; lateral nerves not prominent. Inflorescences 1–6-headed racemes; raceme axes 0.5–2 (–5) mm long, hairy, sometimes glabrous; peduncles (3–) 4–12 (–15) mm long, slender, hairy, sometimes glabrous; heads globular, (18–) 20–36 (–38)-flowered, golden. Flowers 5-merous; sepals variably united. Pods linear, rarely submoniliform, to 9 cm long, (4–) 5–8 mm wide, firmly chartaceous to coriaceous, dark brown or black, often very lightly pruinose, glabrous. Seeds longitudinal, 4–5.5 mm long, subshiny, brown to black, punctate about centre, arillate.

Specimens

S.A.: between Kyancutta and Lock, Eyre Peninsula, N.Hall H80/77 (MEL); Murray Bridge, c. 55 km SE of Adelaide, E.H.Ising s.n. (MEL 615096); Yorke Peninsula, Stansbury 1: 100 000 map no. 6428, grid 404792, B.R.Maslin 4536 (MEL, PERTH). Vic.: Lake Albacutya, A.C.Beauglehole ACB18966 (MEL); Little Desert Natl Park, N.G.Walsh 3582 (MEL).

Notes

B.R.Maslin in Fl. Australia 11A: 357 (2001) suggested that Acacia semiaurea may be a hybrid involving A. retinodes and either A. argyrophylla or the second variant of A. brachybotrya (which is now referable to A. dictyocarpa). See M.O’Leary, J. Adelaide Bot. Gard. 21: 99 (2007), for further discussion.

Until now A. dictyocarpa had been regarded as conspecific with A. brachybotrya, e.g. B.R.Maslin, Flora of Australia 11A: 356 (2001), treated it as the second variant of A. brachybotrya. However, the two species are normally easily distinguished by their branchlet indumentum, the hairs absent or patent in A. brachybotrya and closely appressed in A. dictyocarpa which also has a generally more westerly distribution. In western Vic. the two species may possibly be sympatric (see MEL specimen, Hattah Lakes N.P., A.C.Beauglehole ACB1016) and/or occasionally intergrade. Further study of plants in this area is warranted. Specimens of A. dictyocarpa in S.A., especially from the Eyre Peninsula area, that have golden new shoots closely resemble those of A. argyrophylla. Acacia dictyocarpa is also related to the S.A. endemic, A. spilleriana. The aforementioned four species comprise the ‘A. brachybotrya group’.

The taxon described by J.M.Black, as A. microcarpa var. linearis is now considered to be a hybrid between A. dictyocarpa and A. euthycarpa.

FOA Reference

Flora of Australia Project

Author

B.R.Maslin, J.Reid