Phyllostegia wawrana is a scandent perennial herb becoming woody at the base. Its stems are covered in hirsute hairs, curved or wavy, measuring approximately 0.8–1.3 mm long. The leaves are opposite, ovate to ovate-elliptic, about 10.5–20 cm long and 4–11 cm wide, with a short-acuminate apex and a subcordate base. The leaf surfaces are hirsute, particularly along the veins on the lower surface, and are also glandular-dotted. The leaves have crenate margins and are supported by petioles approximately 4–10 cm long, also hirsute. The flowers occur in leafy, compound racemose inflorescences arising from the upper leaf axils, typically with one short lateral branch bearing a pair of leaves at the base or sometimes with two additional smaller lateral branches. Each verticillaster (an inflorescence that resembles a whorl but consists of two crowded cymes on either side of the stem) has 4–6 flowers, with 9–11 mm long pedicels. The calyx is broadly obconical, around 5 mm long, expanding during fruiting, and features hirsute and glandular-dotted surfaces with usually five linear-deltate teeth about 2.5 mm long. The corolla is bilabiate with a narrow funnelform tube approximately 10 mm long. The reproductive parts include four stamens that ascend the upper corolla lip, and the ovary is superior, 2-carpellate, and has basal-axile placentation. The fruits are about 2 mm long nutlets, dark green to black, and drupaceous, with a fleshy exocarp and slightly winged margins. The seeds lack an endosperm or are scanty and oily. It inhabits diverse mesic to wet forests.