Adromischus sphenophyllus is a low-growing succulent plant that rarely exceeds 25 cm even with a flower stalk. It may branch at the base and form clumps. The leaves are thick with succulence, broader at the tips or obovate with rounded to triangular shape. They have a conspicuous cartilaginous ridge along margin that may be wavy, especially at the top.
There may be maroon spots towards the upper leaf parts or not. Some say only some red colouring near the upper leaf margin and no spots. (There are variations within this plant and similarities to other species, particularly A. maculatus, which show in the photos presented under this name.) Leaf colour may be pale green or blue-grey.
The black leaf discolouring on Adromischus leaves seems to be caused by excessive sun exposure. Plants growing in the shade of shrubs (often renosterbos) show less of this (Bond and Goldblatt, 1984; Shearing and Van Heerden, 2008; www.myweb.tiscali.co.uk).