Lysimachia lydgatei, a member of the Primulaceae (primrose) family, is a sprawling, branched shrub with stems from 1 to 1.3 m (3 to 4 ft) long. Older stems are smooth, but young ones have a dense covering of rust-colored hairs. The leathery, elliptic leaves, 49 to 70 mm (1.9 to 2.8 in) long by 14 to 22 mm (0.6 to 0.9 in) wide, are densely covered with rust-colored hairs. Flowers are arranged singly in the leaf axils. Entire flowers have not been seen, and fruits are capsules about 6 mm (0.2 in) long.