Phyllostegia velutina, of the Lamiaceae (mint) family, is a climbing vine with square stems and dense, backward-pointing hairs on the leaves. The hairs are silky on the opposite, narrow, toothed leaves, which are 9.2 to 17.5 cm (3.6 to 6.9 in) long and 2.5 to 5 cm (1 to 2 in) wide. Six to 10 flowers are borne in an unbranched inflorescence with conspicuous leaflike bracts. The green bell-shaped calyx is 6 to 7 mm (0.2 to 0.3 in) long, densely covered with upward-pointing hairs, and has triangular lobes. The white corolla is densely covered with upward-pointing hairs and is two-lipped, with a slightly curved tube about 12 mm (0.4 in) long, upper lip 5 to 7 mm (0.2 to 0.3 in) long, and lower lip 4 to 5 mm (0.1 to 0.2 in) long. Fruits are divided into four nutlets about 4 to 5 mm (0.1 to 0.2 in) long.