Calochortus bruneaunis is a species of flowering plant in the lily family which is known by the common name Bruneau mariposa lily. It is native to the western United States from California to Montana, where it generally grows in dry, brushy areas. This is a perennial herb producing a mostly unbranching stem up to 40 centimeters tall. The leaf at the base of the stem is narrow in shape, reaching 10 to 20 centimeters long and withering away at flowering. The flower cluster bears 1 to 4 erect bell-shaped flowers. The pointed sepals and larger, rounded petals are white to lilac-tinted in base color. The sepals are marked with a reddish or greenish spot or streak toward their bases and the petals have a greenish streak on the outer surface and a base of yellow, purple, and red coloration on the inner surface. The fruit is a narrow, angled capsule up to 7 centimeters long. It contains several flat, yellow seeds.