Senecio rigidus, the rough ragwort, sometimes called poisonous ragwort, is a robust shrub. It grows branched stems with rough, hairy and longitudinally lined surfaces, reaching heights around 1,5 m.

The small flowerheads are borne in large branched clusters called corymbs, flattish or shallowly rounded in shape. Flowerheads comprise both disc and ray florets, all yellow. The rays, only five or six in number on each flowerhead, are short, elliptic in shape with longitudinal undulations. The small yellow disc protrudes above the ring of ray florets. The individual flowerhead stalks or pedicels have surface scales; so do the involucres.

The species distribution in the Western and Eastern Cape is mainly along the coastal strip, inland in the west to Clanwilliam. The habitat is sandstone slopes, flats and gullies. The plant in the photo was seen on Table Mountain, flowering in November when flowering normally starts and continues to midsummer. The species is not threatened in habitat early in the twenty first century (Manning, 2007; Clarke and Mackenzie, 2007; iSpot; JSTOR).