Acacia tropica (Maiden & Blakely) Tindale, Contr. New South Wales Natl Herb . 4: 273 (1972)
Tall shrub or tree, 3–8 m high, with sparse whippy branches. Bark smooth, later fibrous, grey-brown or red-brown. Branchlets acutely angular, finely striate, glabrous. Phyllodes very narrowly elliptic or sometimes elliptic, straight, 9–16 cm long, 13–41 mm wide, coriaceous, glabrous, with 2–4 prominent nerves (the lower two joined 4–20 mm above phyllode base), the minor nerves 2 or 3 per mm and moderately anastomosing; mucro knob-like; pulvinus 5–10 mm long. Spikes mostly paired in axils, 3–5.5 cm long, very dense, bright yellow. Flowers 5-merous; calyx 0.4–0.5 mm long, dissected by c. , almost glabrous except for marginal cilia and scattered hyaline hairs sometimes along keels and near base; corolla 1.5–2 mm long; ovary densely hairy. Young pods linear, usually flexuose.
Occurs in north-western Australia, the Darwin and Gulf District, N.T., and in Burke District, far north-western Qld as far E as Croydon. Grows in deep sandy soil with Melaleuca viridiflora along watercourses at base of sandstone hills. Flowers June–Aug.
Acacia tropica , which is sometimes placed in the ‘A. cunninghamii group’, is characterised by glabrous branchlets, glabrous peduncles 5–15 mm long, and corollas and calyces persisting on the spikes after the stamens have fallen. According to L.Pedley, Austrobaileya 1: 174 (1978), the widely spaced secondary nerves in the phyllodes of A. tropica indicate that this species may be more closely allied to A. cowleana and A. leptocarpa than to A. concurrens and its relatives.
Type of accepted name
Hell Gate, Roper River, N.T., 2 Aug. 1911, W.B. Spencer ; holo: NSW; iso: K.
Acacia cunninghamii var. tropica Maiden & Blakely, J. Roy. Soc. Western Australia 13: 31, pl. 22, figs 1–5 (1928); Racosperma tropicum (Maiden & Blakely) Pedley, Austrobaileya 2: 356 (1987). Type: as for accepted name.
J.H.Maiden & W.F.Blakely, loc. cit.
N.T.: 30 miles [48 km] E of O.T. Stn, R.A.Perry 1872 (CANB, NSW). Qld: Westmoreland Stn, C.H.Gittins 845 (NSW); ‘Westmoreland’, L.Pedley 2092 (BRI, NSW); 17 miles [27.4 km] SW of Claraville Stn, M.Lazarides 3932 (BRI, CANB, NSW).