Chylismia cardiophylla is a species of evening primrose known by the common name heartleaf suncup.

It is an annual or perennial herb approaching one meter in maximum height, taking the form of a single erect stem or a low bushy plant.

The leaves are up to about 5 centimeters long and are oval or roughly heart-shaped, with rippling or dully toothed edges.

The nodding inflorescence is a dense bunch of flowers, each individual cup-shaped bloom on a stout pedicel.

The flowers are yellow or cream-colored with petals 3 to 12 millimeters long, and generally remain closed during the day.