1	Leaf-blades with craspedodromous venation	Begonia ulmifolia Willd
1’	Leaf-blades with actinodromous venation.
2	Stem rhizomatous, prostrate or decumbent; internodes inconspicuous; stipules persistent; leaf-blades with margin entire or slightly undulate	Begonia pernambucensis Brade
2’	Stem not rhizomatous, erect; internodes conspicuous; stipules caducous; leaf-blades with serrulate margin.
3	Plants covered by microscopic simple and glandular trichomes; stipules triangular; leaf-blades superficially 3–6-lobed, lobes shorter than half the length of their main vein	Begonia reniformis Dryand
3’	Plants covered by microscopic glandular and dendritic trichomes; stipules lanceolate; leaf-blades deeply 6- or 7-lobed, lobes approximately half the length of their main vein	Begonia paganuccii Gregório & J.A.S. Costa