Ripe red tomatoes
The tomato (Solanum lycopersicum) is a herbaceous, usually sprawling plant in the nightshade family that is typically cultivated for its edible fruit. Savory in flavor (and accordingly termed a vegetable; see below), the fruit of most varieties ripens to a distinctive red color.
Tomato plants typically reach to 1–3 metres (3–10 ft) in height, and have a weak, woody stem that often vines over other plants. The leaves are 10–25 centimetres (4–10 in) long, odd pinnate, with 5–9 leaflets on petioles, each leaflet up to 8 centimetres (3 in) long, with a serrated margin; both the stem and leaves are densely glandular-hairy. The flowers are 1–2 centimetres (0.4–0.8 in) across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of 3–12 together. It is a perennial, often grown outdoors in temperate climates as an annual.
Botanically, a tomato is a fruit: the ovary, together with its seeds, of a flowering plant. However, the tomato is not as sweet as most foods eaten as fruit, and is typically served as part of a salad or main course of a meal, rather than at dessert. It is therefore considered a vegetable for most culinary purposes. One exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to be processed in a water bath rather than a pressure cooker as “vegetables” require. Tomatoes are not the only foodstuff with this ambiguity: eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables.
This argument has had legal implications in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables but not on fruits caused the tomato’s status to become a matter of legal importance. The U.S. Supreme Court settled the controversy on May 10, 1893 by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use, that they are generally served with dinner and not dessert (Nix v. Hedden (149 U.S. 304)). The holding of the case applies only to the interpretation of the Tariff Act of March 3, 1883, and the court did not purport to reclassify the tomato for botanical or other purpose.