Acacia decurrens Willd., Sp. Pl . 4th edn, 4: 1072 (1806); see J.H.Ross, Fl. Southern Africa 16: 108 (1975)
Black Wattle , Green Wattle
Tall shrub to tree to 10 (–15) m high. Bark smooth or fissured, brown, greyish black or black, with conspicuous internodal flange marks. Branchlets with winged ridges 0.5–2 mm high, glabrous or sparsely appressed-puberulous. Young foliage-tips yellow. Leaves dark green; petiole above pulvinus (0.7–) 1.5–2.8 cm long, angular, with a prominent, orbicular gland mostly at base of or to c. 7 mm below basal pinnae; rachis 2–12 cm long, angular, furrowed, with orbicular jugary glands at all pairs of pinnae, interjugary glands absent; pinnae 3–13 pairs, (2.5–) 4–7 (–9) cm long; pinnules 15–45 pairs, widely spaced, linear, 5–15 mm long, 0.4–0.8 mm wide, glabrous or rarely sparsely appressed-ciliate, apex obtuse or subacute. Inflorescences in axillary racemes or terminal false-panicles. Heads 20–32-flowered, golden. Pods straight-sided to irregularly and mostly slightly constricted between seeds, 2–10.5 cm long, 4–8.5 mm wide, subcoriaceous, smooth, brown or dark brown, glabrous. 2 n = 26, V.Ghimpu, Compt.-Rend. Hebd. Sances MWm. Soc. Biol. 101: 1122 (1929).
Endemic to N.S.W. chiefly on the coast and tablelands from the Hunter Valley S to the A.C.T.; naturalised in south-western W.A., south-eastern S.A., south-eastern Qld, parts of N.S.W. and A.C.T., Vic. and possibly Tas. The ‘natural’ or native distribution in N.S.W. is confused by naturalisation caused by widespread plantings in the past, including the A.C.T. where it is adventive according to N.T.Burbidge & M.Gray, Fl. Austral. Cap. Terr. 204 (1970). Grows in open forest or woodland, on hillsides or gullies, usually on shale. Flowers mostly July- Sept; fruits Nov.- Jan.
According to J.H.Ross, Fl. Southern Africa 16: 108 (1975), ‘A decurrens is usually attributed to "(Wendl.) Willd." with Mimosa decurrens J.C.Wendl., Bot. Beob . 57 (1798), being taken as a basionym. However, Willdenow cites only Mimosa decurrens Donn, Hort. Cant . 1: 114 (1796) which is a nomen nudum. As he provided no reference to Wendland, either direct or indirect, Willdenow’s binomial must be treated as a new name.’
Acacia decurrens was introduced to South Africa, where it has played an important role in the tanning bark industry. The bark has a high tannin yield but not as high as A. mearnsii .
Hybrids between A. baileyana and A. decurrens are common. Acacia dangarensis is related to A. decurrens .
Type of accepted name
Not designated/ n.v .; probably at B.
Synonymy
Mimosa decurrens Donn, Hortus. Cantabrig. 1: 114 (1796), nom. nud .; Racosperma decurrens (Willd.) Pedley, Austrobaileya 2: 358 (1987). Type: as for accepted name.
Acacia decurrens f. normalis Benth., Fl. Austral . 2: 415 (1864), based on Mimosa decurrens J.C.Wendl., Bot. Beob. 57 (1798). Type: ‘Die Sudsee-Inseln’; ?GOET n.v.
Acacia angulata Desv., J. Bot. Appl. 3: 68 (1814); Mimosa angulata (Desv.) Poir., Encycl. Meth. (Bot.) Suppl. 5: 530 (1817). Type: Nouvelle Hollande, Cote Oriental Voyage aux Terres-Australes, 1801, Capitaine Baudin ; holo: P; iso: BM.
Doubtful names
Mimosa decurrens Duhamel and Mimosa decurrens Vent.: see Doubtful Name.
Illustrations
J.H.Maiden, Forest Fl. New South Wales 3: pl. 87A- L (1907); D.A.Morrison & S.J.Davies, in G.J.Harden (ed.), Fl. New South Wales 2: 390 (1991); D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 307 (1992).
Representative collections
W.A.: Burekup, Bunbury to Brunswick, G.J.Keighery 9104 (NSW, PERTH). S.A.: Basket Ra., H.v.Dam 208 (AD, NSW). Qld: a few miles S of Toowoomba, L.S.Smith 10241 (BRI, NSW). N.S.W.: Menai, P.Hind 5713 & G.D'Aubert (MEL, MO, NSW); 9.5 km SW of junction with Tarago-Goulburn road, L.Thomson 117 (AD, BRI, CANB, K, MEL, NSW, PERTH, US); near Faulconbridge Railway Stn, Blue Mtns, 14 Jan. 1961, M.D.Tindale s.n. (NSW); Old Windsor road-Castle Hill, 30 Aug. 1958, M.D.Tindale s.n. (NSW). A.C.T.: 3 miles [4.8 km] from Queanbeyan on Sutton Rd, H.S.McKee 7348 (NSW). Vic.: Trawalla State Forest, on Western Hwy 0.5 km E of turn-off to Snake Valley, I.C.Clarke 2441 (MEL, NSW).
(MDT & PGK)
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.
