Acacia polystachya A.Cunn. ex Benth., London J. Bot . 1: 376 (1842)
Tree 3–25 m high. Bark smooth to corrugated or coarsely plaited, grey or dark brown. Branchlets angular or flattened, grey, brown or purplish, smooth or pustulate. Phyllodes very narrowly elliptic to narrowly elliptic, sometimes asymmetrical, straight to falcate, 7.5–25 cm long, 10–32 mm wide, chartaceous, glabrous, with 2 or 3 (rarely 4) prominent nerves which run together and often join some distance above phyllode base and remain separate from lower margin, the minor nerves 5–9 per mm, sparingly anastomosing; gland 1, basal, to 3 mm above pulvinus. Spikes 3.5–7.5 cm long, loosely arranged, pale yellow. Flowers 5-merous; calyx 0.4–0.7 mm long, dissected to 1/2, glabrous; corolla 1.6–1.8 mm long, dissected to 1/2, glabrous; ovary densely pubescent. Pods linear, straight-sided to slightly and often irregularly more deeply constricted between seeds, curved to strongly curved and irregularly twisted, 8.5–13 cm long, 6–10 mm wide, thinly coriaceous, blackish, often pruinose, glabrous. Seeds longitudinal, discoid, 3.5–4.2 mm long, black, minutely pitted; pleurogram without halo; areole elongate, open; funicle encircling seed, yellow.
Ranges from Banks Is., Torres Strait, southwards in Cape York along the coast to 17S; also recorded from the Palm Is., Qld. Grows in alluvial soils often near watercourses in semideciduous mesophyll vine thicket and deciduous vine thicket or along beaches. Flowers Apr.–July.
One of the specimens cited in the protologue collected by Armstrong at Port Essington is A. leptocarpa . Although this species is not closely related to A. auriculiformis , it is difficult to distinguish if pods are unavailable. Presumed hybrids involving this species and A. mangium as parents have been collected in Qld. Acacia polystachya is sometimes sympatric with, and superficially resembles, A. midgleyi .
Details of ecology, utilisation etc. are given in J.W.Turnbull (ed.), Multipurpose Austral. Trees & Shrubs 186 (1986).
Type of accepted name
Haggerstone Is., [Qld], 20 Aug. 1820, A.Cunningham ; lecto: K, fide L.Pedley, Austrobaileya 1: 173 (1978).
Racosperma polystachyum (A.Cunn. ex Benth.) Pedley, Austrobaileya 2: 354 (1987). Type: as for accepted name.
J.H.Maiden, Proc. Roy. Soc. Queensland 30: pl. 6 (1918); B.R.Maslin & M.W.McDonald, A key to useful Australian acacias for the seasonally dry tropics , CSIRO, 58 & 59 (1996).
Qld: 106 km by road NNW of Coen along the Kennedy road, R.G.Coveny 7079 & P.D.Hind (A, BRI, CANB, K, L, MEL, TL, US); 5 miles [8 km] from Mossman towards Cairns, C.H.Gittins 1885 (NSW); Fall Ck; Pascoe R., P.Hind 1057 & C.K.Ingram (CANB, MEL, NSW); Yorkeys Knob Beach, Cairns, H.S.McKee 9489 (NSW); Coen, Apr. 1922, N.B.Tindale (NSW).