Description from Flora of China
Bilderdykia Dumortier; Pleuropterus Turczaninow.
Herbs annual, rarely subshrubs. Stems twining. Leaves simple, alternate, petiolate; leaf blade ovate or cordate, margin entire; ocrea tubular, apex oblique or truncate. Inflorescence racemose or paniculate. Flowers bisexual. Perianth persistent, 5-parted; outer 3 tepals larger, keeled or winged, rarely without keels or wings. Stamens 8. Styles very short; stigmas capitate. Achenes trigonous, ovoid.
Between seven and nine species (but ca. 20 if taken more broadly to include Reynoutria): widespread in N temperate zone; eight species (three endemic) in China.
(Authors: Li Anjen (李安仁 Li An-ren); Chong-wook Park)