The sex life of corn involves getting pollen from a male flower to land on a female flower, which leads to development of ears full of kernels that people harvest for a long list of products. Corn is a monoecious plant, meaning that it grows its male and female flowers on the same plant. The male flower of a corn plant is called the tassel, while the ear with its corn silk is the female flower.
The tassel grows at the top of the corn plant, starting as a main stem and adding side branches. Corn plants grow tassels in midsummer, some time between late June and late July. A mature tassel grows pollen-bearing anthers on the stem and branches. The tassel first grows about 1,000 spikelets, each of which contains two florets. Each floret grows three anthers, which generate the pollen. The 6,000 anthers on a tassel hang down from the tassel’s branches.
As the anthers mature, pores open at their tips and the anthers start shedding pollen. Shedding starts in the main stem of the tassel and progresses outward to the branches over a couple of days. Mature tassels shed pollen for about a week. The pollen falling from a tassel resembles a thin cloud of white or yellow dust. A tassel produces vast numbers of near-microscopic pollen grains per day that are carried over the field on the wind. Once shed, a pollen grain stays viable for only a few minutes. When an anther has spent all its pollen, it drops off the tassel.
The corn ears produce their female silk from hundreds of ovules that, if fertilized by pollen, will develop into kernels of corn. The ears start developing silk from their ovules about two weeks before the tassels emerge. Each ovule grows a single strand of silk, starting with the ovules at the base of the ear and working up to the tip. Silk strands can grow up to 1.5 inches per day. Complete emergence of the sticky silk from the ear takes about a week from the time the first silk strands emerge, and coincides closely with tassel maturity.
When a corn pollen grain from a tassel lands on a receptive strand of corn silk, it germinates within minutes. The pollen grain grows a pollen tube that penetrates the silk strand, carrying the male genetic material into the silk. The silk strand carries the male genetic material down to the female ovule that grew the strand. This trip typically takes about 24 hours. The male material unites with the female genetic material in the ovule, fertilizing it so that it will develop into a kernel of corn.
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