Master Gardener talks plant reproduction at Rockwall Newcomers luncheon

Janet Smith, Dallas County Master Gardener

(ROYSE CITY, TX – March 10, 2016) Rockwall County Newcomers and Friends learned some most amusing and remarkable facts about “the birds and the bees” of plant reproduction from guest speaker and Dallas County Master Gardener Janet Smith during a luncheon on Thursday, March 10 at Occasions at Stone River (1250 FM 2453).

Flowers, Smith said, are the reproductive organs of plants, and pollinators their sexual aides. The male organs of a plant are known as stamens and anthers, with the latter producing and releasing the pollen.

“Every species of plant has a unique shape, size and texture of pollen,” Smith said. “Only pollen from the same species can be used to pollinate a plant, so you’re not going to get a cross between a rose and a tulip.”

The ovary and the stigma make up the female organs of a plant. The stigma is usually visible and is what receives the pollen. A plant produces chemicals in the stigma which creates an aroma or stickiness to attract pollinators.

Many times the ovary will be hidden by the petals as a form of protection, as that’s where the seeds will be growing. When the pollen has penetrated the stigma and begins to germinate down in the ovary, pollination, or mating for plants, has successfully taken place.

“Plants know a lot of ways to ensure that things go the way they like them,” Smith said. “They can even determine on that little stigma if the pollen that is deposited there is from their same plant or a different plant, and it gives priority to the pollen from a different plant, because it’s better to have a mix of genes than to have all of your genes from the same family.”

According to Smith, a common method to ensuring that a plant will produce more flowers involves removing the flower which has already been pollinated in a process known as deadheading.

“You can make the plant produce more flowers by deadheading those spent roots, and this is exactly why because the plant produced the flower to reproduce,” Smith explained. “Once it’s pollinated, if you remove that flower, the plant can’t reproduce and has to start over and produce another flower.”

Plants have a wide variety of sexual orientation, and a flower is known as a perfect flower if it has both male and female parts. Some plants have both male and female flowers, and plants can determine their gender by the growing conditions of the season. For instance, a plant will change to male during a drought or similarly harsh conditions and to female during lush conditions.

So why do plants turn male in less amiable growing environments? “That’s because it doesn’t take as much energy to produce pollen as it does to produce the seeds,” Smith said.

Color, shape and aroma decide which pollinators get attracted to which plants. Many pollinators consist of flying insects or mammals such as bats, each of which see different colors of the light spectrum, therefore determining which color flowers will attract them. Bees see blue, yellow, purple and ultraviolet (humans can only see ultraviolet under black light). Hummingbirds see in the red spectrum – red, orange, and purple-red. Butterflies see red, orange, yellow and pink, while flies see green and white and carrion flies (flies attracted to roadkill or dead animals) see maroon and brown.

A lot of flowers are bowl shaped, allowing for pollinators to quickly access their stigmas. Some have built-in protection of their sexual organs, such as fuschias and daffodils. Plants consisting of a group of flowers on one stem – inflorescences – tend to attract large groups of pollinators at one time.

“The pollinators love those because it’s like going to the supermarket: a lot to offer in one place,” Smith said.

A plant will usually only produce an aroma if it believes it necessary to attract pollinators.

“A lot of the night-blooming plants have the strongest scent because if there’s not a full moon, they’ve lost the visual attraction,” Smith said.

Smith added that pollination plays a much more important role in the economy than one might suspect, and makes up an $18-20 billion industry responsible for the production of one third of our food, half of our fats and oils, ingredients in medicines and supplements, and fibers for our clothing. Bees especially play a vital role in the pollination process.

“Honeybees are one of 20,000 species of bees,” Smith said. “They’re a keystone species, which means if you don’t see bees, there is something wrong.”

To keep bees and other pollinators thriving, avoid spraying pesticides and replace plants in your yard with native or old style plants so pollinators will have places to go to get food.

“Plants need bees and we need those plants,” Smith said. “So we are totally dependent on the bees.”

Rockwall County Newcomers and Friends, a social organization for the women of Rockwall County established in 1977, provides support to new and existing community members through its many monthly programs and events. The Newcomers regular program luncheon meetings are held on the second Thursday of the month from September through May, and feature a variety of different guest speakers and interesting topics.