The plant is native to the Southwestern United States, Southern California, and adjacent Baja California, where it grows in sandy areas such as deserts and coastal and mountain scrub habitats.

Calyptridium monandrum is a fleshy, flat annual herb producing short stems which extend along the ground or spread upright from a small taproot.

Thick, spoon-shaped leaves occur in a basal rosette at the base of the stem, reaching up to about 5 cm in length.

Small inflorescences sprout from the stem bearing many flowers, each with fleshy, triangular sepals and three pink or red petals only a few millimeters long.

The fruit is a translucent, oblong capsule up to six millimeters long containing several shiny, black seeds.