Aptenia cordifolia is an evergreen and fast-growing succulent, often a short-lived perennial, 250 mm high. The roots are fleshy and thick. The succulent stems are four-angled or rounded, 600 mm long, and grow flat on the ground. Bladder or water cells are closely arranged on the surfaces of the stems and shine in the sunlight. The green leaves are fleshy, flat, heart- to oval-shaped, 60 x 25 mm long, and are widely spaced in pairs or singularly arranged. Water cells are scattered on the leaf surface.