Acacia trachycarpa E.Pritz., Bot. Jahrb. Syst . 35: 308 (1904)
Resinous spreading shrub or small tree to 5 m high. Bark ‘Minni Ritchi’, red-brown. Branchlets angular towards apices, green and lenticellate between orange-brown, crenulated ridges. Phyllodes oblique, linear, flat, (1.5–) 2–10 cm long, 0.8–3 mm wide, thinly coriaceous, with conspicuous stomates, sub-glabrous or more commonly with often sparse, appressed, silky hairs on nerves and margins (hairs golden on new shoots), with a prominent midnerve and sometimes a subprominent nerve either side, the minor nerves inconspicuous; upper margin broader than the lower; gland 1, basal, to 6.5 mm above pulvinus. Spikes 9–20 mm long, golden. Flowers 5-merous; calyx 0.5–0.9 mm long, dissected to 1/5–2/3 or more, golden-hairy; corolla 1.2–1.7 mm long, dissected to 1/4–5/8, glabrous. Pods mostly straight-sided to scarcely constricted between seeds, curved to circinnate, flat, 3–11 cm long, 7–12 mm wide, coriaceous, finely reticulately nerved, sericeous when young, later glabrescent. Seeds oblique, rotund or round, flattened, depressed towards centre, brown to black, pitted; pleurogram with yellowish grey halo; areole round or oblong, closed, greyish brown.
Occurs in the Pilbara region of W.A. Grows mainly in sandy clay loam derived from alluvium, also a variety of habitats (see notes). Flowers May–Aug.
Acacia trachycarpa is a polymorphic species. Typical A. trachycarpa is a spreading, obconic tree or shrub 4–5 m high with phyllodes mostly 4–10 cm long. It normally grows on broad levees or the banks of rivers and creeks. An apparent ecotype of A. trachycarpa occurs sporadically throughout its range. This form has phyllodes 2–4 cm long and grows as a spreading shrub up to one metre high. It has been recorded from a range of sites which include: coastal dunes (Finucane Is., Anon. 273 , PERTH), gravelly, spinifex plains (5.1 km E of Nullagine, L.Thomson 1149 , PERTH), road verges (11.5 km E of Wittenoom on road to Port Hedland, B.R.Maslin 4645, PERTH) and rocky ranges (Barlee Range Nature Reserve, 19.2 km SE Mt Florrie, S. van Leeuwen 1583, PERTH).
An undescribed variant of A. trachycarpa occurs in the Great Sandy Desert–Lake Mackay region of central Australia (e.g., 16 June 1957, G.Chippendale NSW253368; P.K.Latz 12853, AD, BRI, DNA, K, NT, PERTH). This taxon is keyed and described separately in WATTLE as A. affin. trachycarpa .
Acacia trachycarpa has affinities with A. chisholmii , A. effusa , A. gracillima and A. lysiphloia . It hybridises with A. ancistrocarpa , fide B.R.Maslin, Nuytsia 4: 405; 406, fig. 13 (1983), A. eriopoda (Mt Edgar, N.T.Burbidge 1117 , PERTH) and A. tumida , fide L.A.J.Thomson et al ., Journal of Arid Environments 27: 162–163 (1994). Note: in WATTLE the hybrid between A. ancistrocarpa and A. trachycarpa is keyed and described separately, as A. ancistrocarpa x trachycarpa .
Introduced into West Africa for firewood and stock fodder. Further details on its utilisation are given in J.C.Doran & J.W.Turnbull (eds), Austral. Trees & Shrubs: species for land rehabilitation and farm planting in the tropics 134–135 (1997).
Type of accepted name
Harding R., Roebourne, W.A., 18 Apr. 1901, L.Diels 2755 ; lecto: PERTH (Fragment ex B) n.v ., fide B.R.Maslin, Nuytsia 4: 99 (1982).
?Acacia gonocarpa var. lasiocalyx F.Muell., Pl. NW Australia 1: 8 (1881). Type: ‘Yule and Fortescue Rivers. Jones’ Creek and Georges River, J.Forrest’; n.v ., synonymy following B.R.Maslin, loc. cit .
M.Simmons, Acacias Australia 1: 247 (1987); B.R.Maslin & M.W.McDonald, A key to useful Australian acacias for the seasonally dry tropics , CSIRO, 72 & 73 (1996).
W.A.: 42 miles [67.2 km] E of Dampier, F.Lullfitz 6156 (CANB, K, MEL, NSW); Port Hedland, I.V.Newman 674 (NSW); Fortescue R., Millstream, M.I.H.Brooker 2056 (MEL, NSW, PERTH); Nullagine, F.Lullfitz 6185 (CANB, K, NSW).