Long-leaved bluets is a perennial herb with upright, slender, branching stalks arising from a basal rosette of leaves. Flowers are on slender stems arising from upper leaf axils, in loose or crowded clusters, minute, white or pinkish, with 4 petals that are hairy on the inside surface. Blooms April–July. The basal leaves are in a rosette, narrow, and linear. The stem leaves are opposite, oblong to linear. Both types have only one central vein.
Similar species: There are six other species of bluets in Missouri.