Senecio cotyledonis, in Afrikaans known as stinkbos (stink bush), is a shrub reaching heights from 60 cm to 1 m. The much-branched, thickish stems are brittle, pale grey and smooth, usually bare apart from near their tips as the leaves drop off early.

The succulent leaves are long, narrow and somewhat triangular in cross-section, their tips pointed. The leaf surfaces are blue-green, glabrous and often longitudinally lined. Leaf dimensions are about 5 cm long and 3 mm wide. The leaves exude and unpleasant odour when damaged.

The flowerheads grow stalked in stem-tip clusters. A flowerhead consists of one row of narrow, green bracts forming a cylindrical involucre below a sparse ring of spreading, yellow, female ray florets around a small disc of five-lobed, bisexual and also yellow florets. The flowerheads are about 1 cm in diameter. Flowering happens in winter and early spring.

The species distribution is in the Western Cape excluding the far westerly part, slightly into the south of the Northern Cape and the northwest of the Eastern Cape. The photo was taken southwest of Oudtshoorn.

The habitat is karoid scrub veld, succulent Karoo and renosterveld, where the plants grow on semi-arid, clayey and stony flats and lower slopes. The species is not considered to be threatened in its habitat early in the twenty first century. The plant is not browsed, usually seen in abundance in poorly managed veld (Vlok and Schutte-Vlok, 2015; Bond and Goldblatt, 1984; iNaturalist; http://redlist.sanbi.org).