Phyllostegia helleri is a weakly erect to climbing perennial herb; stems with hairs 0.5 to l mm (0.02 to 0.03 in) long. Leaves are thin, somewhat wrinkled, ovate, 10 to 14.5 cm (3.9 to 5.7 in) long, 3.5 to 6.5 cm (1.4 to 2.6 in) wide, hairy, inconspicuously glandular-dotted, margins with rounded to pointed teeth, leaf stalks 2.5 to 5 cm (1 to 2 in) long and also hairy. Flowers are 6 per false whorl, in leafy, compound, inflorescences usually 8 to 19 cm (3 to 7.5 in) long, consisting of the primary branch and two to several lateral branches immediately below. Flower stalks are 3 to 5 mm (0.1 to 0.2 in) long, hairy, with sepals narrowly bell-shaped. Corolla is white with lobes tinged lavender. Nutlets are about 2.5 mm (0.1 in) long.