Flora of Australia Online

Acacia holosericea A.Cunn. ex G.Don, Gen. Hist. 2: 407 (1832)
Soap Bush, Silver-leaved Wattle.

Acacia mangium var. holosericea (A.Cunn. ex G.Don) C.T.White, Contr. Arnold Arbor. 4: 42 (1933); Racosperma holosericeum (A.Cunn. ex G.Don) Pedley, Austrobaileya 2: 349 (1987). T: Repulse Bay [South Repulse Is., Qld], 1819, A.Cunningham 317 ; neo: BM, fide B.R.Maslin & L.A.J.Thomson, Austral. Syst. Bot. 5: 737 (1992). Note: The lectotypification of this name by L.Pedley, Austrobaileya 1: 181 (1978), based on Cunningham 478 was overturned by B.R.Maslin & L.A.J.Thomson, Austral. Syst. Bot. 5: 737 (1992).

Acacia holosericea var. glabrata Maiden, Proc. Roy. Soc. Queensland 30: 48 (1918). T: Gilbert R., Qld, E.W.Bick comm. C.T.White ; holo: NSW; iso: BRI.

Acacia holosericea var. multispirea Domin, Biblioth. Bot. 89: 270 (1926). T: in xerodrymio apud rivulum prope opp. Chillagoi, Qld, Feb. 1910, [K. ]Domin '5176' ; holo: PR.

Acacia holosericea var. typica Domin, Biblioth. Bot. 89: 270 (1926), nom. inval.

Illustrations: K.A.W.Williams, Native Pl. Queensland 1: 7 (1979); J.Brock, Top End Native Pl. 63 (1988); B.R.Maslin & L.A.J.Thomson, Austral. Syst. Bot. 5: 736 (1992).

Shrub or tree 3–8 m high. Branchlets acutely angled but normally ±terete by 20–30 cm below apex, usually sericeous, sometimes glabrous. Young shoots silvery sericeous, sometimes glabrous. Phyllodes obliquely narrowly elliptic, 10–20 cm long, normally 2–5 cm wide, with unequal base, usually sericeous; mucro 1–3 mm long; normally 3 prominent nerves per face confluent and contiguous with abaxial margin at base; minor nerves forming a somewhat open longitudinally orientated reticulum; glands basal and at base of mucro on at least some phyllodes. Inflorescences rudimentary racemes with axes to 0.5 mm long; peduncles 3–7 mm long, sericeous, sometimes glabrous; spikes normally 2–4 cm long, golden; bracteoles linear-spathulate, 1–1.5 mm long. Flowers 5-merous; sepals united. Pods tightly and often somewhat irregularly coiled, 2.5–4 mm wide, thinly crustaceous to coriaceous-crustaceous, ±glabrous, remaining as entangled clumps following dehiscence. Seeds longitudinal, oblong-elliptic, 3.5 mm long, shiny, dark brown; aril bright yellow. Fig. 37M–P.

Widespread in northern Australia extending from near Derby, W.A., E across the N.T. to near Rockhampton in eastern Qld. Also scattered occurrences in arid regions at Hamersley Ra. Natl Park, W.A., through central N.T. and to SW of Blackall, Qld. Grows in sometimes gravelly sand or loam, commonly forming communities along watercourses. Map 245.

W.A.: Barker R., 2.5 km S of Mt Hart HS, D.J.Edinger 455 (BRI, DNA, PERTH); Hancock Gorge, Hamersley Ra. Natl Park, M.E.Trudgen 1370 (BRI, PERTH). N.T.: Mini Mini Ck, 22 km WSW of Murgenella Settlement, J.H.Ross 3331 (MEL n.v. PERTH); Mt Ultim, Dulcie Ra., B.G.Thomson 2182 (DNA). Qld: Budgerygar, SW of Yaraka, C.F.Puttock AQ421303 (BRI).

Branchlets and phyllodes are sometimes glabrous but more commonly they are sericeous with appressed or subappressed hairs; only rarely are the branchlets pubescent with spreading hairs (e.g. Petford, Qld, N.Hall H83/63, PERTH). Specimens with the widest phyllodes occur in the northern parts of Qld and the N.T. (e.g. Elco Is., J.R.Maconochie 2147, BRI, CANB, DNA, L) and may sometimes resemble A. neurocarpa, but they seem to be A. holosericea on account of their short, linear-spathulate bracteoles and their slender branchlets which, although apically angled, are soon terete. The phyllodes of A. colei often superficially resemble those of A. holosericea.

In the light of genetic studies by G.F.Moran et al. (1992), in A.House & C.Harwood (eds) Australian Dry-Zone Acacias for Human Food (CSIRO, Canberra), the taxonomic status of A. holosericea was reviewed by B.R.Maslin & L.A.J.Thomson, Austral. Syst. Bot. 5: 729–743 (1992). Consequently A. holosericea is now more narrowly defined, and A. neurocarpa and A. colei are now excluded from it (see the latter two species for further details). Some of the species related to these three include A. cowleana, A. elachantha, A. grandifolia, A. mangium, A. nesophila, A. pellita and A. sericoflora.

Phyllodes, bark and pods are used traditionally by N.T. Aborigines for pruritic skin conditions, headache and tropical infection, fide, Aboriginal Communities of the Northern Territory (1993), Traditional Aboriginal Medicines N. Territory Australia 16–19 (Conservation Commission of the Northern Territory of Australia, Darwin).

(B.R.Maslin)