Potatoes are one of the world’s most important food crops. Most people are familiar with planting a “seed potato,” which is actually a small piece of the tuber itself. This common practice often leads to the mistaken belief that potatoes do not produce a true botanical seed. However, the potato plant, Solanum tuberosum, does reproduce sexually and produces a small, hard-shelled fruit that contains genuine seeds. These botanical seeds are known as True Potato Seeds (TPS) and are primarily used by breeders and researchers.
The True Potato Seed vs. the Seed Potato
The terminology surrounding potato planting can be confusing because the word “seed” is used to describe two different things. A “seed potato” is not a seed in the botanical sense; it is a tuber, which is an enlarged, underground stem used for vegetative or clonal propagation. Planting a seed potato ensures the resulting plant is an exact genetic clone of the parent, guaranteeing consistency in traits like yield and flavor.
The True Potato Seed (TPS), in contrast, results from sexual reproduction—the pollination of a potato flower. Each TPS is genetically unique, meaning the tubers produced by a plant grown from TPS will differ from the parent plant and from each other. Commercial growers rely on the clonal consistency of seed tubers, making TPS a less common method for large-scale food production.
Visual Characteristics of True Potato Seeds
True Potato Seeds are remarkably small, resembling the seeds of other nightshade family members like tomatoes, but on a much smaller scale. Each seed measures approximately 1 to 2 millimeters in diameter. A single potato fruit, or berry, can contain between 200 and 300 seeds.
When extracted and dried, the seeds are typically oval-shaped and possess a hard, protective outer coat. Their color ranges from a pale, light tan to various shades of brown, sometimes appearing nearly black. Due to their minute size, TPS requires careful handling and is often started indoors in controlled conditions, much like starting tomato seedlings.
The Potato Fruit Where Seeds Develop
True Potato Seeds develop inside a small, round fruit that forms on the above-ground part of the potato plant after pollination. This fruit is often called a potato berry or a potato ball and is rarely seen in modern commercial fields. The berry looks similar to a small, green cherry tomato or a tomatillo, which is expected since both belong to the Solanaceae (nightshade) family.
The potato berry typically ranges from 0.5 to 2.0 centimeters in diameter. This fruit is highly toxic and should never be consumed by humans or animals. The toxicity comes from high concentrations of glycoalkaloids, primarily solanine and chaconine. These compounds are concentrated in the fruit, making it dangerous to ingest.
Propagation Methods Using True Potato Seeds
While tubers dominate commercial agriculture, True Potato Seeds are used for specific, high-value applications. The primary use of TPS is in potato breeding programs and by plant geneticists. Generating new genetic combinations through sexual reproduction is the only way to develop new potato varieties with improved traits.
Planting TPS allows researchers to screen thousands of genetically unique plants to find those with greater disease resistance, better adaptability to changing climates, or superior culinary qualities. The seeds also offer logistical advantages: they are lightweight, easily stored, and less prone to transmitting certain diseases compared to bulky tubers. For example, only 25 to 100 grams of TPS are needed to propagate an entire hectare of potatoes, compared to 2 to 3 tons of seed tubers.