Description from Flora of China
Herbs, perennial, erect, robust, basally lignified, 0.8-4 m tall, yellow lactiferous. Roots stoloniferous. Stems glaucous, terete, hollow, herbaceous, smooth. Leaves alternate, petiolate; blade pale glaucous abaxially, green or blue-green adaxially, broadly ovate or suborbicular, abaxially pilose or glabrous, adaxially glabrous, basal veins usually 5, lateral veins 1-3 pairs, veinlets netted, base cordate, usually 7- or 9-lobed, apex acute, obtuse, acuminate, or rounded; lobes undulate to serrulate. Flowers small, many forming large terminal panicles. Flower buds clavate or terete. Sepals 4, milky. Petals absent. Stamens 8-12 or 24-30; filaments filiform, not longer than anthers; anthers oblong. Ovary 1-loculed, 2-carpellate; ovules 1 or 4-6, basifixed or bilaterally attached; styles very short; stigmas 2-lobed. Capsule narrowly obovoid, oblanceolate, or suborbicular, shortly petiolate, 2-valvate. Seeds 1 and basifixed, or 4-6 and bilaterally attached, ovoid.
Two species: China and Japan; two species (one endemic) in China.
(Authors: Zhang Mingli (张明理); Christopher Grey-Wilson)