Acacia didyma A.R.Chapm. & Maslin, Nuytsia 8: 264; 261, fig. 4A (1992)
Dense, rounded shrub or tree 1.5–4 m high. Branchlets pruinose, glabrous. Phyllodes orbicular to widely elliptic, 2–5 cm long, 1.5–4 cm wide, obtuse, subfleshy with age, glaucous, lightly pruinose, glabrous, 2-nerved, imperfectly 3–4-nerved on broadest phyllodes; lateral nerves not prominent, anastomoses few, sometimes obscured by wrinkling; glands 2, lowermost 1–8 mm above pulvinus, uppermost at base of mucro. Inflorescences normally 4–12-headed racemes; raceme axes 2–4 cm long; peduncles twinned, 5–10 mm long, rather stout, glabrous; heads globular, subdense, c. 20-flowered, golden. Flowers 5-merous; sepals united into a truncate calyx. Pods strongly curved to openly once-coiled, to 10 cm long, 12–15 mm wide, coriaceous-crustaceous, lightly pruinose, glabrous, outer margin shallowly undulate. Seeds longitudinal, widely oblong-elliptic, 4.5 mm long, shiny, dark brown to black; aril large, yellow-brown (dry).
Scattered in the Shark Bay area where it occurs on Dirk Hartog Is. and Carrarang and Tamala Stns, also on East Wallabi Is. in the Houtman Abrolhos Group, W.A. Grows in sand on limestone ridges and consolidated dunes in scrub and shrubland.
A member of the ‘ A. bivenosa group’ distinguished from the more northerly A. bivenosa and A. startii , and the more southerly A. telmica and A. xanthina , by racemes with twinned peduncles, large, strongly-curved to openly once-coiled, flat pods and orbicular to widely elliptic phyllodes (l:w = 1- 2).
Type of accepted name
3.6 km W of Tamala HS road, on Useless Loop Rd., Shark Bay, W.A., 31 Aug. 1988, A.R.Chapman 601 ; holo: PERTH; iso: CANB, G, K, MEL, NY.
Acacia elliptica A.Cunn. ex Benth., London J. Bot. 1: 347 (1842) p.p. , not as to lectotype, as to A.Cunningham  , Dirk Hartog Is., fide A.R.Chapman & B.R.Maslin, op. cit. 256.
[ Acacia bivenosa auct. non DC.: G.Bentham, Fl. Austral. 2: 381 (1864) p.p. , as to A.Cunningham , Dirk Hartog Is.]
[ Acacia xanthina auct. non Benth.: B.R.Maslin & L.Pedley, Res. Notes W. Austral. Herb. 6: 126 (1982), as to grid cell 201]
A.R.Chapman & B.R.Maslin, op. cit. 261 .
W.A.: 1.6 km W of causeway, near Carrarang Stn, T.E.H.Aplin 3432 (PERTH); Tamala Stn, B.R.Maslin 3699 (CANB, K, PERTH); East Wallabi Is., 8 Sept. 1959, G.M.Storr (PERTH).
(ARC & BRM)