Do you remember biology class in high school? Most of us learned about how plant reproduce, and how pollen is moved from one plant to another to fertilize them. So how do tomatoes reproduce asexually? What is the explanation behind this almost immaculate conception dealio? Read on to learn how these delicious fruits are created from single flowers.
How do Tomatoes Reproduce Asexually? How Can One Plant Produce its Own Fruit?
The answer to this is a bit complicated. You see, they don’t reproduce asexually at all. They reproduce sexually, but are self-fertile. If this confuses you, you’re not alone.
For a plant to propagate itself (reproduce), it needs to produce seeds. This means that it needs both male and female genetic material to work with. This is the entire reason why many plants produce flowers. Those flowers, once pollinated, will develop into fruits containing seeds.
To go into that a bit more, in botany, there are both “imperfect” and “perfect” types of flowers.
We call tomato flowers “perfect”. This isn’t because they’re perfect examples of nature’s majesty in action, but because they contain both male and female organs within them. They don’t need other flowering plants nearby in order to be fertilized. Instead, they produce both the male and female parts needed to create new life. These types of plants are quite hardy, because they don’t depend on other plants to cross-pollinate them. The downside is that they can be prone to mutations and other health issues that normally happen with inbreeding.
Further Reading: Why do Tomatoes Turn Black on the Bottom, on the Vine?
In contrast, an “imperfect” flower is one that is either male OR female. For example, members of the Cucurbitaceae family, such as cucumbers, squashes, pumpkins, and melons produce either male or female flowers. These need to cross-pollinate in order to reproduce. Insects such as bees and butterflies gather the pollen from the male flowers and transfer it to the female ones.
This type of cross-pollination generally results in more abundant, healthier fruits. They tend to be more disease-resistant, and often create really interesting hybrids.
Tomato Botany Basics
We’ve covered some of this in our article on how greenhouse tomatoes reproduce, but let’s go into a bit more detail, shall we?
Your typical perfect flower (such as a tomato blossom) will have four primary parts: sepals, petals, stamens, and pistils.
Sepals are the protective outer bud parts, while petals are the colorful bits that attract bees, butterflies, and other pollinators. Tomato flowers are generally yellow, but you’ve seen all manner of flower petals before, and they come in every hue imaginable.
When it comes to the tomato flower’s reproductive organs, we have stamens and pistils. The stamen is the male part, which consists of a filament (a stem-like part) with a pollen-covered anther at the top. In some flowers, the stamens are individual, branching tendrils. In tomato plants, however, they’re fused into something that looks like a yellow tube.
The female reproductive part is the pistil, which is made up of a stigma, style, and ovary. The stigma is a sticky opening on top of the style (tube), which catches pollen as it’s deposited by a pollinator, or flies past on the wind. The ovary lies at the pistil’s base, and contains the ovules: they contain the female genetic information necessary for reproduction. As soon as these ovules are fertilized with pollen, the combined genetic material from both male and female parts (known as their “gametes“) merge and develop into seeds!
You know all those seeds inside every tomato fruit? Each and every one of those seeds have all the information needed to grow into new plants… which will then flower and repeat this entire dance all over again.
As you can see, this isn’t asexual reproduction, but self-fertility.
What if My Tomato Plant Isn’t Producing Fruit?
There are a few reasons why this can happen.
One issue that can happen is if you’re growing the wrong tomato cultivar for your climate. Different fruits and vegetables have evolved to survive and thrive in particular circumstances. For example, a Calabash tomato plant from Mexico isn’t going to do well in Norway. Similarly, a Purple Russian tomato plant will keel over and die if grown in Morocco.
If your tomato plants aren’t fruiting, try to get some new ones that have been cultivated in your own area, or growing zone.
Another issue can be that there’s something wrong with the pollen. Tomatoes like heat and sunshine, but too much heat can sterilize their pollen. If you’re living in an area where nighttime temperatures aren’t dropping below 75F/24C, then your tomatoes might go sterile. In a case like this, definitely aim for heat-resistant varieties, as they’ll the only ones that will be able to bear fruit in your region.
Additional Reading: Why are My Tomatoes Turning Yellow Instead of Red?
Humidity (or the lack thereof) can also cause problems. In areas where humidity is very high, the pollen can clump up into a kind of mud. It can’t move over to the stigma to pollenate. In contrast, if the weather is really dry, the flower parts shrivel up. The stigma dries up instead of being sticky, so any pollen that lands on it will just slide right off again. No fertilization = no tomatoes.
So, as you can see, the answer to “how do tomatoes reproduce asexually?” is simply that they don’t. Their reproductive cycle offers a fascinating glance into the wide world of self-fertile angiosperms. Now that you’re enthralled with all things tomato-related, you might want to pick up some (local!) seeds and start growing your own!