The five unequal sepals of Apatesia helianthoides are flat and leaf-like, varying in length and shape. Usually oblongs, they are thinly succulent sometimes with unexpected elongation and tip shapes. The three inner, smaller sepals may have membranous margins, the two outer ones may exceed the petals in length.

The sepals unite at the flower base into a nearly flat, saucer-shaped limb, united with the inferior ovary.

There is a ring-shaped nectary in the flower base for the benefit of pollinators (Le Roux, et al, 2005; Leistner, (Ed.), 2000; Eliovson, 1990; Herre, 1971; iNaturalist).