Annual, with stiff, erect branches, 10-100 mm tall. Leaves sessile, elliptic to obovate, dorsiventrally flattened and almost membranous, 6-12 x 4-6 mm. Flowers in loose clusters, on slender, spreading pedicels, cup-shaped, petals ± 1 mm long, white.
Like C. oblanceolata but flowers smaller, petals ± 1 mm long, and ovary tuberculate.