Most floral nectar proteins (nectarins) are reported to function in nectar defence, particularly for insect-pollinated outcrossing species. Zha et al. compare nectarin composition in selfing common tobacco (CT; Nicotiana tobaccum) to outcrossing ornamental tobacco plants and find that the most abundant nectarin in CT nectar is an acidic alpha–galactosidase that has not been detected in the nectar of outcrossing sister species. CT fruits do not develop intact skin with galactose inhibition of a-Gal activity in the nectar. The results indicate that floral nectarins in selfing species maintain their functional significance in reproductive organ development.