Begonia acetosa Vell.

Leaves ovate, acuminate, to 8 cm long, olive green satiny surface with white, bristly hairs; red below with scattered hairs; margins finely toothed, hairy. Flowers small, white.

Brazil

Source: Wright, P.; Goodwin, J.; Spencer, R. (1997). Begoniaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Rosanae
order      Cucurbitales
family       Begoniaceae
genus        Begonia L.