Typically, up to 1000 ovules form per ear, even though we typically harvest only 400 to 600 actual kernels per ear. Silk elongation begins 7 to 10 days prior to silk emergence from the husk. Complete silk emergence from an ear generally occurs within two to seven days. Silks from the basal portion of the ear typically emerge first, while the tip silks generally emerge last. For those of you serious about semantics, let's review two definitions relevant to sex in the corn field.
Pollination is the act of transferring the pollen grains to the silks by wind or insects.
Fertilization is the union of the male gametes from the pollen with the female gametes from the ovary. A pollen tube, containing the male genetic material, develops and grows inside the silk, and fertilizes the ovary within 24 hours. Pollen grains can land and germinate anywhere along the length of an exposed silk. Many pollen grains can germinate on a receptive silk, but typically only one will successfully fertilize the ovary. Silk receptivity to pollen grain germination exists up to 10 days after silk emergence.