How Do Tomatoes Spread Their Seeds?

Tomato plants thrive in sunny spots with well-drained soil.

The tomato is a perplexing plant. With a low sugar content and savory flavor, it tastes like a vegetable, even though it is a fruit, reproducing by means of seeds and pollination. The tomato plant's method of reproduction might not be obvious, since the seeds are encased within the fruit and, unlike many fruit seeds, may be consumed along with the flesh. Tomatoes are capable of spreading seeds through natural methods, but typically, they reproduce with a gardener's help.

Self-Pollination

Modern varieties of tomato plants usually self-pollinate, resulting in generations of plants that are genetically similar.

Pollination occurs when the tomato plant is in flower. The stigmata of the tomato become receptive the day before the flowers first bloom and the pollen begins to spread before the flower is fully open. The pollen continues to spread for anywhere from one day to one week after the flower opens, depending on the conditions.

Under natural conditions, the stamens of the flowers on modern tomato plants, which are responsible for producing pollen, are fused together and the anthers, where pollen is stored, are on the inside of the fused stamens. Pollen spreads on the inside of the flower and the plant naturally self-pollinates.

Cross-Pollination

Modern tomato plants do not usually cross-pollinate, meaning that hybrid cultivars do not often occur naturally. Older varieties of tomato plants are more readily capable of cross-pollination because their flowers do not feature fused stamens and the pollen is exposed to pollinator insects such as bees. These insects are more commonly attracted to tomato plants in areas like the tropics.

Fertilization

Fertilization is what produces the fruit and seeds of the tomato plant. The pollen grains of the flower germinate and produce root-like pollen tubes. The tube grows down into the plant and extends into the plant's ovary and penetrates one of the plant's ovules. Fertilization occurs when the female sex germ within the ovule combines with the male sex germ within the pollen tube. The fertilized ovule becomes one of the seeds of the tomato plant.

Natural Seed Dispersal

Each seed of the tomato plant is enclosed in a protective, soft casing. The casing contains natural chemicals that keep the seed dormant and prevent it from germinating within the moist, warm environment of the tomato flesh.

In a natural environment, the seeds are dispersed when overripe fruit falls off the vine and begins to rot. The seeds are exposed and the process of decomposition destroys the seed's casing so that it is able to germinate.

Seed Cultivation

Farmers and gardeners often replicate the natural process of seed dispersal in tomato plants to cultivate a plant that grows well and produces good fruit. To do this, they harvest ripe fruits and deliberately allow them to rot and ferment.

In this method of seed dispersal and reproduction, tomato fruits are cut into halves and the interior of the fruit with the seeds is scooped out into a container. The gardener adds a little water to speed the process and lets the mixture sit for a few days until mold forms at the top of the container. Once this occurs, the fermentation process is complete and the seeds must be removed before they begin to germinate within the container. Seeds are rinsed and dried and may then be stored in jars or sachets until ready to be planted.

References

• Kokopelli Seed Foundation: Tomato Pollination and Seed Production
• University of Illinois Extension: Watch Your Garden Grow
• University of California Davis: Tomato Fertilization