Herbs perennial, evergreen. Rhizomes creeping, slender. Leaves all basal, petiolate; stipules absent; leaf blade elliptic or broadly to narrowly ovate, leathery, margin serrate. Panicle or raceme with small bracts. Sepals (4 or)5(-7). Petals absent. Stamens (8-)10; anthers distinctive in comprising only 2 microsporangia. Carpels 2, connate proximally; ovary very shallowly subsuperior, appearing almost superior, proximally 2-loculed with axile placentation and distally 1-loculed with marginal placentation. Fruit a capsule. Seeds numerous, small, acute at both ends.

Tanakaea is closely related to the monotypic Leptarrhena R. Brown (from the Pacific Northwest of North America), which possesses the same distinctive anther morphology.

One species: China, Japan.

(Authors: Pan Jintang; Douglas E. Soltis)