Phyllostegia hirsuta, a member of the Lamiaceae (mint) family, is an erect subshrub or vine with stems densely covered with coarse or stiff hairs. The wrinkled leaves are egg-shaped, 17 to 30 cm (6.7 to 12 in) long, and 7.3 to 18 cm (2.9 to 7 in) wide. Both leaf surfaces are moderately covered with long, flat hairs. The upper surface is inconspicuously dotted with glands, while the lower surface is more densely glandulose. The egg-shaped floral bracts are 3 to 6 mm (0.1 to 0.2 in) long. The flowers have two lips—the upper one is approximately 3 mm (0.1 in) long and the lower one is 5 to 7 mm (0.2 to 0.3 in) long. The tubular portion of the flower is slightly curved. The corolla is white and usually purple-tinged on the upper lip. The fruit is a nutlet about 3 mm (0.1 in) long.