The Homeowners Column

The Homeowners Column

Revealing the Sex Life of Plants

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

We grow many plants for their ornamental flowers or fruits. Despite what we may think, it's not really all about us – but it is all about sex. Plant sex that is. Flashy fruits and flowers are designed to attract pollinators to the flowers or entice animals to eat the fruit to process and/or distribute seeds. Horticulturists have super-beautified some plants by selectively breeding for our sense of good looks to the point where the plant's animal companions hardly recognize them.

Plants have divergent ways to optimize their chances for reproduction. A typical flower diagram includes male and female reproductive parts, colorful petals and green leaf-like sepals. In other words mom and dad share a bedroom. Once the female parts are pollinated by pollen from the male parts, the seeds and fruit will form. Apple and rose are examples of plants with this basic arrangement.

However nature loves diversity and not all flowers contain functional male and female parts. With some plants mom and dad live in the same house, but stay in separate bedrooms. These plants have male flowers and female flowers on the same plant. They rely on insects or the wind to move the pollen from the male flower to the female flower. Examples include squash, birch, begonia, and oak.

With other plants their male and female flowers are separated even further onto separate plants. In other words mom and dad live in separate houses. In order to get fruit, female plants and male plants need to grow in relative close proximity for proper pollination and therefore fruit to form. Generally one male can pollinate 3-4 females.

So why all this sex talk? Fruit is often an important ornamental feature. Wildlife including people also enjoy fruit as food. Home gardeners are known to illicit any number of fruitful comments such as: "it's beautiful"; "it's tasty"; "it's messy"; "it's gross"; "it stains"; "it stinks"; or "it's dangerous". Sometimes we want fruit and sometimes fruit is our yearly curse.

Depending on the plant we may need to select the proper sex to enjoy or avoid fruit. Many of our landscape plants have male and female plants. If fruit is desired the female is preferred with a token male nearby for pollination. If fruit is undesirable, the male plant is preferred.

Generally the male is preferred in: ash, ginkgo, honey locust, Kentucky coffeetree, mulberry, Osage orange, and poplar. The females of honey locust and Kentucky coffeetree produce large pods which are fine in natural settings, but can be a mess in home landscapes. Female ginkgo trees have odiferous fruit. It's fun to watch people walk under ginkgos in the fall. Odds are they will check the bottoms of their shoes for evidence of Fido's morning ritual.

Landscape plants in which the female is preferred (however at least one male plant must be nearby for fruit to form): bittersweet; bayberry; holly; spicebush; sumac; and persimmon.

Keep in mind some male plants can have a few complete flowers so a few fruits may still form, but not as abundantly as with female plants. Look for cultivated varieties (cultivars) with obvious boy or girl names or check resources in order to get the plant sex of your choice. These have been produced asexually by cuttings or grafting to ensure the plant's sex. 'Autumn Gold' and Princeton Sentry ® are good male ginkgos. Our love-hate relationship with mulberries is expressed in some local notable cultivars. 'Urbana' is a weeping fruitless form named by the late U o f I professor, J.C. McDaniel. 'Illinois Everbearing' produces several crops of tasty mulberry fruit.

Telnet program

How Insecticides and Miticides Work on Tuesday October 24, 1:00 p.m. at Champaign County Extension office 801 North Country Fair Drive in Champaign.

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