The leaves of Pelargonium spinosum come in two sizes. Both are kidney-shaped and pale green: The larger ones are 2 cm in diameter and bear the persistent petioles turned spines. The smaller ones, 1,5 cm in diameter, grow on deciduous petioles from the axils of the bigger leaves.
Both leaf types are shallowly lobed and sparsely, somewhat angularly toothed, about square at the base. Leaf surfaces are fleshy and glabrous (hairless) apart from a few glandular hairs.
The leaf petioles have stipules at the base, also hardening to become thorns, 4 mm long (Frandsen, 2017; Le Roux, et al, 2005; www.bihrmann.com; www.pelargonium.si).