Acacia longifolia (golden wattle).

A. longifolia has commonly been recognized as having two variants - var. longifolia and var. sophorae. Biochemical and morphological evidence, presented by Murray et al. (1978) and Pedley (1978), suggests that var. longifolia and var. sophorae should be treated as distinct species. However, this view has not been adopted in a number of recent works, notably Whibley and Symon (1992) and Tame (1992). Further research is required to ascertain if differences in habit, morphology and habitat warrant acceptance at a higher taxonomic level. Variety longifolia occurs as a tall shrub or small tree up to 10 m tall, usually with relatively thin, linear-lanceolate phyllodes 6-15 cm long and 3-15 mm wide. Its pods are more or less straight and 3-6 mm wide. Its natural distribution extends from northern New South Wales south to Victoria and South Australia along coastal hinterlands and adjacent ranges. It grows a on range of sites in open forests or woodlands. Variety sophorae is a low spreading, prostrate shrub, 2-5 m and up to 15 m wide, with relatively thick, obovate oblong or oblong elliptic phyllodes, 5-10 cm long and 12-35 mm wide. Its natural distribution extends along the coast in southeast Queensland, New South Wales, Victoria and west to the Eyre Peninsula in South Australia. This variety is restricted to coastal foredunes where it forms dominant stands. A. longifolia has fast growth and is mainly grown for its ability to stabilise sand dunes (e.g. Berenhauser, 1973; Kosmer, 1975; Avis, 1989). However, in a number of countries, notably South Africa, these plantings have resulted in A. longifolia becoming a serious weed species, invading and displacing native vegetation. Integrated control operations to eradicate A. longifolia in South Africa started as early as 1943 and have had variable results (Macdonald et al., 1989). More recently, the introduction of biological controls agents, such as gall-forming wasps, have apparently been effective in locally eradicating the species (Dennill and Gordon, 1990; Dennill and Donnelly, 1991; Moll and Trinder-Smith, 1992; Manongi and Hoffmann, 1995). However, the wasps are reported to have spread to plantations of the commercially important tree species A. melanoxylon (Dennill et al., 1993). A. longifolia is also reported to have established naturalised populations in California and New Zealand (Whibley and Symon, 1992). A. longifolia is planted as an ornamental in Spain and has been trialled for its potential as a source of gum arabic in Corsica (Vassal and Mouret, 1989; Trigo and Garcia, 1990). Recently, it has also been grown as a successful substrate for the production of oyster mushrooms in South Africa (da Serra and Kirby, 1999). The seeds of var. sophorae were traditionally used as food by Australian Aborigines (Isaacs, 1987).