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Knowledge to Grow by Karen Weiland - Pollination


The definition of pollination is the transfer of male pollen grains from the anther to the stigma on a plant in order to fertilize the ovaries of a flower. After a grain of pollen reaches the ovary, cells are discharged from the pollen grain where they unite with female sex cells. After the fertilization process is completed, the ovule matures into a seed and the ovary enlarges to form a fruit. Some examples of these fruits would be oranges, apples and grapes. Some plants produce other types of seed holding vessels like beans or peppers.

Dioecious plants have separate male and female flowers but are born on separate plants such as holly and bittersweet. For fruits to develop on a holly plant you will need to plant a cultivar bearing female flowers and separate plant of the same cultivar type planted nearby that will bear male flowers. Monoecious plants have separate male (bearing stamens) and female (bearing pistils) flowers on the same plant such as cucumbers. Female flowers can usually be identified as they have an ovary directly behind or within the bloom which normally looks like a small, immature fruit. This summer take a look at your cucumber flowers. The female flower will have a tiny area between the flower and the vine that looks like a small cucumber and the male flower will not. So there you have Sex Identification of a Cucumber Flower 101.

You may have read the term self-pollinating when browsing seed catalogs. This refers to the process when pollen is transferred within the same flower or different flowers on the same plant such as peppers and strawberries. Another term along the same line is cross-pollination. In this process, flowers must receive pollen from a different plant of the same plant type for fruit to be set. This transfer of pollen is done through the wind or by honeybees, moths, butterflies and birds.

Unfortunately, many parts of the world are seeing a decline in native pollinators. Many of the fruits and vegetables we enjoy depend on insect pollinators. The honeybee is particularly adapted for gathering pollen and thus is widely used for the pollination process in crops requiring pollination. Zac Browning, vice president of the American Beekeeping Federation, estimates that “every third bite we consume in our diet is dependent on a honeybee.”

As always, Happy Gardening!

More information about gardening and related subjects is available online at www.hort. The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County.