Senecio venosus, in Afrikaans commonly known as besembos (broom bush), is a perennial herb growing annual, unbranched stems from a woody rootstock to heights of about 1 m. The inflorescence is a flat-topped panicle of many small, yellow flowerheads that only sometimes have ray florets around the discs. It flowers in spring.
The stalkless, stem-clasping leaves are blue-green or glaucous and elliptic. They are lobed at the base, tapering to acutely pointed tips and have entire margins. Leaf venation is notably translucent against the light. The specific name, venosus, refers to these conspicuous veins.
The species distribution is widespread in South Africa north of the Vaal River. The habitat is grassland and bushveld. The species is not considered threatened in its habitat early in the twenty first century (Van Wyk and Malan, 1997; www.redlist.sanbi.org).