Yellow endosperm in Coffea arabica is determined by recessive gene (ce ce) ; single, double and triple doses of the dominante Ce determine the normal green color. Such a xenia mechanism has been used in this investigation to determine the; speed of pollen tube penetration through the style. The stigmata of protected flowers were pollinated simultaneously, or at intervals of hours with both Ce and ce pollen. The styles were eliminated after a certain time had elapad. It has been found that, even though seedless fruits are formed in coffee, fruit development is not stimulated it the pollen tube does.nospenetrate into the ovary. Pollen tubes from foreign pollen grew faster through the cera styles than proper cera pollen tubes. In the first case, 24 to 48 hours elapsed between pollination and pollen tube penetration into the ovary; in selfing this process took 48 to 63 hours. Comparing these results with those previously obtained for the varieties typica, semperflorens and Mundo Novo, it can also be concluded that speed of pollen tube penetration varies according to the variety and environmental conditions.