Acacia Dealbata, the silver wattle, blue wattle or mimosa, is a species of flowering plant in the legume family Fabaceae, native to southeastern Australia in New South Wales, Victoria, Tasmania, and the Australian Capital Territory, and widely introduced in Mediterranean, warm temperate, and highland tropical landscapes.

It is a fast-growing evergreen tree or shrub growing up to 30 m tall, typically a pioneer species after fire. The leaves are bipinnate, glaucous blue-green to silvery grey, and the leaves resemble that of a fern. 1–12 cm (occasionally to 17 cm) long and 1–11 cm broad, with 6–30 pairs of pinnae, each pinna divided into 10–68 pairs of leaflets; the leaflets are 0.7–6 mm long and 0.4–1 mm broad.

The flowers are produced in large racemose inflorescences made up of numerous smaller globose bright yellow flowerheads of 13–42 individual flowers.

The fruit is a flattened pod 2–11.5 cm long and 6–14 mm broad, containing several seeds. Trees generally do not live longer than 30 to 40 years, after which in the wild they are succeeded by other species where bushfires are excluded. In moist mountain areas, a white lichen can almost cover the bark, which may contribute to the descriptor "silver".

The Latin specific epithet dealbata also means "covered in a white powder". The Wiradjuri people of New South Wales use the name Giigandul for the species.