The domesticated tomato, Solanum lycopersicum, is one of the world’s most widely grown food crops. While all cultivated tomatoes share a single species designation, thousands of distinct varieties, or cultivars, exist globally, making an exact count impossible. Experts categorize this immense diversity based on how the plant grows, the physical attributes of the fruit, and the plant’s genetic history.
Classification by Growth Habit
Tomato plants are fundamentally classified by their growth pattern, a distinction used by growers to determine planting and maintenance needs. This classification is divided into two primary types: determinate and indeterminate. The growth habit dictates the plant’s final size and its fruit production timeline.
Determinate tomato plants, often called “bush” varieties, grow to a genetically set height, usually between three and five feet tall. Once the terminal bud produces a flower cluster, the stem’s vegetative growth stops. This results in a concentrated harvest, where the majority of the fruit ripens all at once over a few weeks. Determinate types are valued for mechanical harvesting and canning because uniform ripening allows for a single, large-scale pick.
Indeterminate tomato plants are considered “vining” varieties because they continue to grow, flower, and set fruit continuously until frost stops them. These plants can reach heights of ten feet or more, requiring substantial support like staking or trellising. The indeterminate growth habit provides a steady supply of fruit over the entire growing season, making these varieties popular for home gardens and fresh market consumption.
Classification by Size and Use
Tomatoes are commonly grouped based on the physical characteristics of the fruit, which influences its traditional culinary use. These categories are often the most familiar to consumers. Variation in size, shape, and internal structure, such as the ratio of pulp to dense flesh, dictates how the fruit is best utilized.
Small-fruited varieties include Cherry and Grape tomatoes. Cherry tomatoes are typically round with a high water content and juicy interior. Grape tomatoes are generally smaller and oblong, possessing denser flesh and less water than cherry types. Both are prized for snacking and salads due to their high sugar content.
Plum or Roma tomatoes are defined by their elongated, cylindrical shape and dense, meaty texture. This structure results in low seed and water content, making them ideal for processing. They are the preferred choice for making thick sauces, pastes, and canning, as their flesh yields a concentrated flavor.
The Standard Globe tomato is the traditional, mid-sized variety often referred to as the slicing tomato. These round tomatoes offer a balanced profile of acidity and sweetness, making them versatile for general kitchen use. Beefsteak tomatoes are the largest category, known for their flattened, irregular shape and substantial size. Their firm, meaty texture makes them the top choice for use in sandwiches or grilling, where a thick, stable slice is necessary.
Classification by Genetic Origin
The final classification addresses the tomato’s breeding history and genetic stability, which impacts seed saving and flavor consistency. This division separates varieties into two main types: heirloom and hybrid.
Heirloom tomatoes are defined as open-pollinated varieties passed down through generations. Open-pollination means the plants are pollinated naturally, and their seeds will “breed true,” producing offspring identical to the parent plant. This genetic stability allows gardeners to save seeds year after year. Heirloom types are celebrated for their complex flavor profiles and unique shapes, though they often lack the disease resistance and uniform appearance of modern commercial varieties.
Hybrid tomatoes are the result of deliberate, controlled cross-pollination between two specific parent varieties. The resulting seeds are known as F1 hybrids, bred to express desired traits such as disease resistance, uniform ripening, or extended shelf life. While F1 hybrids offer predictability and vigor, seeds saved from their fruit will not grow true to the parent type in the next generation. This breeding method allows for the rapid development of varieties tailored for specific commercial requirements, such as shipping or greenhouse production.