is a perennial herb inhabiting forests in mountainous regions. Stems
measure 15-30 cm in height, and the lower parts sparsely branch,
with hairs on one side. Leaves are of opposite phyllotaxis in an
oval shape. T. japonicum is dioecious; it has membranaceous
stipules at the bases of petioles and sets 1 or 2 novel shapes of
male or U-shaped female flowers. The male flowers hang many stamens,
and three sepals bend backward around. Bloom time: April-May.