Acacia nilotica subsp. indica (Benth.) Brenan, Kew Bull . 1957: 84 (1957)
Prickly Acacia , Babul
Spreading, dense shrub or tree to 12 m high. Bark smooth, becoming rough and longitudinally fissured at base. Branchlets sparsely to moderately pubescent especially when young, sometimes glabrous, often slighty pruinose. Stipular spines mostly 2–50 mm long, often diminutive and appearing absent on some branchlets. Leaves: petiole (0.4–) 0.9–2 cm long, pubescent, mostly with a gland at or just below base of lowest pair of pinnae; rachis (0.3–) 0.8–6.8 cm long, pubescent, with a small gland at apex, rarely with a gland at base of second pair of pinnae from apex; pinnae (1–) 2–6 (–10) pairs, 1–4.5 cm long; pinnules 9–30 pairs, narrowly oblong to cultrate or slightly oblanceolate, 1.7–7 mm long, mostly 0.5–2 mm wide, obtuse to broadly rounded at apex, concolorous, with numerous stomata, glabrous or sparsely ciliolate, with midnerve not raised beneath and lateral nerves not visible. Inflorescences simple, 2–6 in axils; peduncles 7–32 mm long, with involucel of bracts mostly 1/2–3/4 way from base; heads globular, 30–53-flowered, yellow to bright yellow. Mature pods narrowly and regularly constricted between seeds into orbicular sections, flat, 6–25 cm long, 14–17 mm wide (2–4 (–9) mm wide at constrictions), coriaceous, grey- or white-tomentose, sticky inside, indehiscent.
Native of India but naturalised in tropical Qld from Bowen and Hughenden S to Rockhampton and Barcaldine, and to a lesser extent in the N.T. and north-eastern S.A. on Clifton Hills Stn ( fide D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 294 (1992); possibly a garden escape in places; may form dense thorny thickets, in grassland, woodland and sometimes open forest, common on cleared land, usually along roadsides and on open plains or floodplains, often near creeks, streams, dams or bores, in silty, heavy (cracking) clay or sometimes sandy alluvial soils. Flowers recorded Jan., Apr.–June, Aug.–Sept., probably throughout year; fruits recorded May, Sept. and Oct.
When its characteristic tomentose, necklace-like pods are not available, specimens of A. nilotica subsp. indica can usually be distinguished from A. farnesiana by its branchlets being hairy with less lenticels, and its pinnules without distinct lateral nerves raised beneath. There are 8 other subspecies of A. nilotica ( fide J.H.Ross, Mem. Bot. Surv. S. Africa 44: 106, 1979) which are not recorded as naturalised in Australia. A less hairy specimen of what appears to be A. nilotica with pinnules to 3.2 mm wide was collected in W.A., viz . Gascoyne R., Carnarvon, Sept. 1941, C.A.Gardner (PERTH), however further collections from W.A. have not been seen. Specimens of cultivated or possibly escaped plants of A. nilotica have been collected from N.S.W., though some are atypical and require further investigation.
Initially introduced into Rockhampton, Qld, in the late 1800s as a source of gum arabic, fide R.W.Johnson, Proc. Roy. Soc. Queensland 105: 12 (1995). Subsequently cultivated as an ornamental and grown as a fodder and shade plant, particularly in parts of tropical Qld. Has a high weed potential in pastures. The pods of A. nilotica have been used in tanning and in folklore medicine. Gum exudates and stem bark extracts are also used for medicinal purposes. Notes on habitat, life cycle, origin and distribution, control, etc. are provided by H.E.Kleinschmidt & R.W.Johnson, Weeds of Queensland 196 (1977), A.N.Gracie, Agnote No. 525 (1992) and W.T.Parson & E.G.Cuthbertson, Noxious Weeds of Australia 435 (1992).
Type of accepted name
India, ‘East India’, Dr Roxburgh ; syn: K; Oungein, coll. unknown ( Jacquemont ?) in Herb. Bentham; syn: K.
Acacia arabica (Lam.) Willd. var. indica Benth., London J. Bot . 1: 500 (1842); A. nilotica var. indica (Benth.) A.F.Hill, Bot. Mus. Leafl. 8: 99 (1940). Type: as for accepted name
J.P.M.Brenan, in C.E.Hubbard & E.Milne-Redhead (eds), Fl. Trop. East Africa, Leguminosae subfam. Mimosoideae 67, fig. 16/37a, pod only (1959); W.T.Parsons & E.G.Cuthbertson, op. cit . 436- 437; D.J.E.Whibley & D.E.Symon, op. cit. 31; E.Anderson, Pl. Central Queensland 31 (1993).
N.T.: Darwin, C.E.F.Allen B30 (NSW). Qld: 4 miles [6.4 km] S of Bowen, M.Fogg 681 (CANB, NSW); near Hughendon Township, M.Lazarides 3518 (CANB, NSW, PERTH); 1 mile [1.6 km] NW of Winton, Landsborough Hwy, I.V.Newman 565 (NSW). S.A.: Cordillo Downs HS, W.S.Reid 120 (ADW).