The Collaborative International Dictionary of English v.0.48:

maple-leaf begonia \maple-leaf begonia\ n. (Bot.)
   A tuberous or semi-tuberous South African begonia (Begonia
   dregei) having shallowly lobed ovate leaves and small white
   flowers.

   Syn: grape-leaf begonia.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

maple-leaf begonia
    n 1: tuberous or semi-tuberous South African begonia having
         shallowly lobed ovate leaves and small white flowers [syn:
         grape-leaf begonia, maple-leaf begonia, Begonia
         dregei]