Senecio glossanthus is an annual herb native to Australia. In Western Australia it is commonly known as slender groundsel.
It grows as an erect annual herb, reaching up to in height, though normally not more than high. It is sparsely hairy, with few branches except for the branched inflorescence. The flowers are yellow.
It was first published as Erechtites glossantha by Otto Wilhelm Sonder in 1853. In 1867, George Bentham transferred it into Senecio as S. brachyglossus, but this was later considered an illegitimate name because it unnecessarily replaced Sonder's specific epithet. In 1956, Robert Orange Belcher effected a legitimate transfer by publishing the name Senecio glossanthus.
It is widespread in temperate parts of the Australian mainland, occurring in every mainland state.