lily of the valley, common name for either of the two species of Convallaria, spring-blooming perennials of the family Liliaceae (lily family). C. majalis, the species usually in cultivation, is native to Eurasia; C. montana, a slightly larger plant, grows in the Appalachian Mts. Lilies of the valley live in shady places and have delicate bell-shaped, fragrant white flowers growing on a stalk between two shiny leaves. The plant was long used medicinally for cardiac disorders and contains poisonous substances. It is a symbol of humility in religious painting. Lily of the valley is classified in the division Magnoliophyta, class Liliopsida, order Liliales, family Liliaceae.