Acacia rivalis J.M.Black, Trans. & Proc. Roy. Soc. S. Australia 42: 173; pl. 18, figs 5–8 (1918)
Silver Wattle , Creek Wattle
Obconic shrub or tree 3–5 m high; crown bushy and domed. Branchlets ultimately pendulous, normally glabrous. Phyllodes linear, 4–14 cm long, 2–5 mm wide, acute to acuminate and often curved towards apex, thin, glabrous, 1-nerved per face, finely penninerved; gland 15–40 mm above pulvinus. Inflorescences racemose; raceme axes 2–5 cm long, slender, sparsely to moderately appressed-puberulous, with hairs dense and pale golden when young; peduncles 4–10 mm long, with indumentum as on raceme axes; heads globular, densely 30–40-flowered, bright yellow; bracteoles bright golden-fimbriolate. Flowers 5-merous; sepals united to near apex, the lobes bright golden-puberulous. Pods moniliform, to 16 cm long, 4–4.5 mm wide, firmly chartaceous to thinly coriaceous, glabrous. Seeds longitudinal, oblong to elliptic, 5–6 mm long, dull, black; funicle 1/2–3/4 encircling seed in a single fold, red-brown; aril clavate.
Occurs in S.A. from Hawker N to near Mt Harris, North Flinders Ra., and also near L. Bring and Wilgena, c. 500 km to the west. Recorded from near Broken Hill, N.S.W., but possibly not native there, fide S.W.L.Jacobs & J.Pickard, Pl. New South Wales 150 (1981). In S.A., the species grows in tall shrubland on ridges and rocky shaly hills or along watercourses, in shallow calcareous loam.
A member of the ‘ Acacia microbotrya group’ which possibly hybridises with A. araneosa in the northern part of Flinders Ra., S.A. Also related to A. retinodes which is distinguished by its often wider, normally oblanceolate to narrowly oblanceolate phyllodes with the gland 1–10 mm above the pulvinus, glabrous raceme axes and peduncles, and linear pods 5–7 mm wide.
Putative hybrids between A. calamifolia and A. wattsiana (Nectar Brook variant) may superficially resemble A. rivalis.
Type of accepted name
Hawker, S.A., 18 Oct. 1917, J.M.Black ; holo: AD; iso: AD, MEL.
Illustrations
J.M.Black, loc. cit .; M.Simmons, Acacias Australia 149 (1981); T.Tame, Acacias SE Australia 152, fig. 166, pl. 166 (1992); D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 131 (1992).
Representative collections
S.A.: Balcanoona, near Nudlamutana Well, Hj.Eichler 19642 (AD, K, MEL, PERTH); near L. Bring, Commonwealth Hill Stn, B.Lay 791 (AD, PERTH). N.S.W.: Mundi Mundi Ck, 8.5 km N of Umberumberka Ck which is 35 km NW of Broken Hill, I.B.Armitage 976 (NSW, PERTH).
(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.
