Senecio maritimus leaves are oblong, sometimes widened into ovate or obovate shapes with rounded to pointed, often blunt tips. The leaf bases taper to the stem or are eared at the base without stalks. The leaves sometimes have variably toothed margins, the teeth sometimes rounded.

The soft green blades are thinly fleshy, the midribs sunken on the upper surfaces (Manning, 2007; Manning and Goldblatt, 1996; Bond and Goldblatt, 1984; iNaturalist).