From the fabulous folks down at Seed Savers Exchange in Decorah, IA, a great article explaining plant pollination:
How your plants pollinate
By: JUNE 14, 2012 | No Comments| Published:
Our teaching garden at Seed Savers Exchange demonstrates important seed saving concepts. Throughout the season, I’ll take you on a tour to discuss some of these concepts. The first stop on our tour is the Pollination bed. It is important that seed savers understand how their plants pollinate in order to prevent varieties in the same species from cross-pollinating. In this bed we are growing tomatillos, spinach, amaranth and cucumbers to demonstrate different flower types.
Flowers exist to facilitate pollination, which occurs when pollen is transferred from the male anther to the female stigma. In some plants, this occurs before the flower even opens. In other plants, pollinators such as humans, insects, or wind are required to transfer the pollen.
Tomatillos have perfect flowers. These flowers have both male and female organs, allowing for self-pollination. Tomatillos are “selfers” that can pollinate before their flower even opens.
Selfers are good plants to choose if you are a beginning seed saver. Selfers include tomatoes, peppers, beans, peas, and lettuce. And remember, in nature there are always exceptions to the rule—just because a plant can self-pollinate doesn’t mean that it can’t cross pollinate.
Spinach and cucumber have imperfect flowers. These flowers have either male or female organs. If male and female flowers are on different plants, the species isdioecious. In order to produce seed, pollen must travel from male plants to the female plants. Spinach is dioecious, and requires the wind to pollinate. Asparagus is also dioecious, and relies on insects for pollination.
Cucumber flowers are imperfect as well. However, cucumbers—as well as squash, melons, watermelons, and gourds—are monoecious, with male and female flowers on the same plant. Notice the immature fruit at the base of the female flower pictured above. In the Cucurbitaceae family, insects are required to transfer pollen from male flowers to female flowers for pollination to occur. Corn is also a monoecious plant with imperfect flowers (the tassels represent the male flowers, and the developing ears represent the female flowers), though corn relies on wind for pollination.
Take a few minutes to identify male and female flowers in your home garden. Congratulations you are officially one step closer to becoming a seed saver!