Phyllostegia parviflora var. lydgatei is a shrubby perennial herb with stems densely covered in antrorsely strigose hairs, which become hirsute and glandular hirsute throughout the inflorescence. The leaves are simple and opposite, with ovate to broadly ovate blades measuring (15–)19–33 cm in length and (6–)7.5–15.3 cm in width. The leaf apex is acuminate, and the base ranges from truncate to rounded or subcordate. The surfaces are conspicuously glandular-dotted, mainly when dry, with the upper surfaces being appressed long-hirsute and the lower surfaces hirsute to antrorsely strigose, particularly along the veins. The blades are rugose, and the margins are crenate. The flowers number (4)6(10) per verticillaster (inflorescence that resembles a whorl but consists of two crowded cymes on either side of the stem) in leafless, compound, racemose inflorescences typically 10–20 cm long. The inflorescences consist of a terminal primary stem and numerous secondary and tertiary lateral branches, covered in hirtellous and sparsely to moderately glandular hirtellous hairs. The calyx is campanulate, 3–6 mm long, and enlarges in fruit. It is hirtellous, with conspicuous nerves and glandular-dotted surfaces. The corolla is bilabiate, 10–13 mm long, white with a purple tinge on the upper lip. The ovary is superior, 2-carpellate, with basal-axile placentation. The fruit comprises nutlets approximately 3–6 mm long, dark green to black, drupaceous, with a fleshy exocarp and slightly winged margins. The seeds lack an endosperm or are scanty and oily. It is found in mesic forests between 730-825 meters.