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Backyard Plant Breeding

Close up of a yellow flower. 

Pollination is what gives us the fruits and vegetables we like to eat and seeds for the future. Whether you know it or not, flowers are not just different in appearance from plant to plant, but the ways in which they are pollinated and turn info fruit are different as well.

Some plants have “perfect” flowers where both male and female parts are present, such as roses, apples and dandelions. These flowers may or may not be self-pollinated. Depending on species genetics, some plants can self-fertilize, like tomatoes and beans, and others require cross-pollination, like apples.

Other flowers are “incomplete,” meaning that they have separate male and female flowers. Some incomplete plants are monoecious and have distinct but separate male and female flowers on one plant, like squash, cucumbers and corn.

There are a few ways to tell male and female flowers apart when it comes to members of the cucurbit family. First, look at the base of the flower. If the base is swollen and looks like a tiny version of the mature fruit, then it is a female flower. If the base is just a straight stem, then it is a male flower. The second method is to look inside the flower. If there is one large central structure – called the pistil – that indicates the flower is female. Male flowers have several, smaller stamens inside. Female flowers also tend to be larger than male flowers.

For the female squash blossom, life revolves around attracting honey or other native bees that have recently visited male flowers to assure pollen transfer. All members of the cucurbit family require this pollination technique to make sure the female flowers produce fruit.

Each species and variety of squash have a different ratio of male to female flowers. The ratio is usually about one-to-one, but it is not unusual to see varieties with many more male flowers than female. Many of the plants also produce an abundance of male flowers early in the season to makes sure bees are attracted to the plant later on to pollinate the female flowers. 

If a majority of early flowers die without setting fruit or about half of the flowers die throughout the season, there is nothing to worry about because they were probably male flowers. On the other hand, if female flowers are dying throughout the season without producing fruit, there is a definite problem. This means that there were no bees or other pollinators available to pollinate the plants. 

If fruits have shrunken parts or are misshapen, then there could be an incomplete pollination issue from not having bees around. This could result from not having enough food for the bees in the area to encourage their presence or from weather being too cool or wet for bees to get out and pollinate. It also could be the result of improper use of pesticides in the area. 

You can take matters into your own hands if you notice a lack of birds, bees and other pollinators in your garden. Transferring pollen from male to female flowers can be accomplished using a small artist’s paintbrush or simply pulling off a male flower and using it to apply pollen directly to the female flower.

This method is often used by plant breeders or those who want to save seed of crops that easily cross-pollinate. Hand pollination is often followed by bagging the flower to keep pollen or pollinators away to avoid accidental unwanted pollen.  

Easy cross-pollination of varieties is why the most common heirloom crop varieties you will find are tomatoes and beans. Both of these crops have closed flowers that help resist cross-pollination. They are most likely to be self-fertile, meaning that the flower will pollinate itself without outside assistance. This helps the plant breed true, meaning that you should end up with somethings that is similar to what you had this year. 

If you want to save something that is bee-pollinated, like your squash, pumpkins or cucumbers, you might want to use the brush and bag technique or you might end up with a surprise in the garden next year. 

By  Mary Beth Bennett , WVU Extension Agent – Berkeley County.