When the catkins mature, huge quantities of pollen are shed, increasing the chances that the windblown pollen will land on the stigmas of the female flowers. Should the catkins mature before or after the female flower is receptive, pollination does not occur. The fruits develop only after the female flowers are pollinated and the ovules are fertilized by male cells from the pollen. Usually, within a pecan cultivar, pollen shedding does not closely overlap the period when the stigma is receptive. This condition is called dichogamy, which tends to ensure cross-fertilization.
Pecan cultivars differ in the order that the male and female flowers mature.
I and II should be included in a planting. I bloom class are Cape Fear, Desirable and Owens. Type II bloom class includes Elliott, Forkert, Gloria Grande and Stuart. Cape Fear is a good pollinator for many other cultivars. It has adequate scab resistance but experiences severe leaf scorch in many locations.