Acacia argyrophylla Hook., Bot. Mag. 74: t. 4384 (1848)
Silver Mulga
Dense shrub 2–3 m high and often the same across, closely allied to A. brachybotrya but differing mainly in the following ways. New shoots sericeous with bright greenish yellow hairs. Penultimate branchlets sericeous with white hairs. Phyllodes oblanceolate, 2.5–5 cm long, 6–15 mm wide, sometimes to 6 cm long and 2.5 cm wide at base of branchlets, l:w = 2–4.5, obtuse, silvery blue-grey due to sericeous indumentum of silvery white hairs completely covering the lamina. Inflorescences racemose with axes normally 4–10 mm long and with dense, appressed, greenish golden hairs; peduncles c. 10 mm long, with indumentum as on racemes except hairs occasionally silvery white; heads 25–45-flowered. Pods 7–11 mm wide. Seeds 5–7 mm long.
Occurs in S.A. from the Flinders Ranges near Hawker S to Monarto and the western Murray Mallee region, with isolated populations occurring on the Yorke Peninsula and Onkaparinga Gorge. An isolated occurrence from near Cromby, Vic., is now presumed extinct, fide A.B.Court, in J.H.Willis, Handb . Pl. Victoria 2: 222 (1973). It grows on low hills and slopes in woodland and mallee, often in alkaline soils.
The status of A. argyrophylla deserves further attention. J.H.Maiden, loc. cit ., treated it as a variety of A. brachybotrya , but later considered it a distinct species, fide J. & Proc. Roy. Soc. New South Wales 53: 202 (1920). As defined here, A. argyrophylla is narrowly circumscribed and is most readily distinguished from A. brachybotrya by longer phyllodes which are densely clothed with silky appressed hairs (bright greenish yellow on new shoots, silvery white on mature phyllodes). Some specimens currently referred to A. brachybotrya , especially those from the Yorke Peninsula, S.A., may possess certain of these characters but they do not occur in combination as in A. argyrophylla . In some cases hybridity between the two species is suspected. Acacia semiaurea may be a hybrid involving, perhaps, A. retinodes and A. argyrophylla or A. brachybotrya (appressed-hair variant) .
Type of accepted name
Cultivated at Kew Gardens, London [protologue erroneously gives the provenance as Swan R., W.A.]; holo: K.
Synonymy
Acacia brachybotrya f. argyrophylla (Hook.) Benth., Fl. Austral. 2: 374 (1864); A. brachybotrya var. argyrophylla (Hook.) Maiden, Forest Fl. New South Wales 6(3): 47, pl. 200O (1914). Type: as for accepted name.
Acacia bombycina Benth., Paxton’s Fl. Gard. 2: 101, fig. 186 (1851). Type: cultivated [protologue erroneously gives the provinence as Swan R., W.A.]; n.v. , synonymy following G.Bentham, Fl. Austral. 2: 374 (1864).
Acacia argyrophylla F.Muell.: see Doubtful names.
Illustrations
L.F.Costermans, Native Trees & Shrubs SE Australia 311 (1981); T.Tame, Acacias SE Australia 121, fig. 124b, pl. 124b (1992); M.Simmons, Acacias Australia 2: 163 (1988); D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 73 (1992).
Representative collections
S.A.: Loxton, T.R.N.Lothian s.n. (AD9620781); l.5 km N of Monarto South on the road to Monarto, B.R.Maslin 5974 (AD, K, PERTH); 36.3 km E of Kimba, J.G. & M.H.Simmons 1140 (AD); Onkaparinga Recreation Park, R.Taplin 370 (AD, PERTH); 32 km NE of Hawker, R.F.Telfer 6 (AD); near Minlaton, D.J.E.Whibley 6200 (AD). Vic.: near Coromby, 5 Oct. 1892, F.Reader 3 (MEL).
(BRM)
The information presented here originally appeared on the WATTLE CD-ROM which was jointly published by the Australian Biological Resources Study, Canberra, and the Department of Parks and Wildlife, Perth; it was produced by CSIRO Publishing from where it is available for purchase. The WATTLE custodians are thanked for allowing us to post this information here.
