Abstract
Begonia medogensis JianW.Li, Y.H.Tan & X.H.Jin, a new species of Begoniaceae, is described and illustrated by colour photographs. Begonia medogensis is distributed in western China and northern Myanmar. It has erect stems, is tuberless, has many triangular to lanceolate leaves, base slightly asymmetric, margins remotely and irregularly denticulate; staminate flowers have 4 perianth segments, with outer 2 segments broadly ovate, inner 2 spathulate; pistillate flowers have 5 perianth segments, unequal, outer 4 broadly ovate, inner 1 spathulate. The new species is assigned to section Platycentrum and can easily be distinguished from the other species in the section.