The leaves of Senecio erosus are mostly basal. They are long and narrow, oblong to oblanceolate. The margins are lobed or roundly toothed, maybe scalloped, the margins rolled under. Note the frond-like sassy style of the youngest leaf.
The soft green and hairy blade halves bulge next to the sunken midrib that thickens lower down. At the base it becomes a winged petiole or all still part of a sessile leaf, depending on how one looks at it (Manning and Goldblatt, 1997; Bond and Goldblatt, 1984; iNaturalist).