Silene alexandri, a member of the pink family (Caryophyllaceae), is an erect, short-lived perennial herb, 30 to 60 cm (1 to 2 ft) tall, and woody at the base. The narrow, elliptic leaves are 30 to 65 mm (1.2 to 2.5 in) long by 6 to 14 mm (0.2 to 0.6 in) wide, and hairless except for a fringe along the margins. Flowers are arranged in open clusters with stalks 10 to 19 mm (0.4 to 0.7 in) long. The 5-lobed, 10-veined, tubular calyx is 19 to 25 mm (0.7 to 1 in) long, and the 5 white, deeply-lobed, clawed petals extend about 4 to 6 mm (0.2 in) beyond the calyx. The capsule is about 14 to 16 mm (0.6 in) long, but seeds have never been seen. The hairless stems, flowering stalks, and sepals and the larger flowers with white petals separate this species from other members of the genus.