Acacia sclerosperma, commonly known as limestone wattle or silver bark wattle, is a tree in the family Fabaceae. Endemic to Western Australia, it occurs on floodplains and along water-courses throughout the arid north-west corner of the State. There are two subspecies: Acacia sclerosperma subsp. sclerosperma and Acacia sclerosperma subsp. glaucescens. The latter is commonly known as billy blue, and is currently considered under threat, though not yet endangered.