Limes are a member of the citrus family, which also include oranges, grapefruit, mandarins and lemons. There are only two species of commercially valuable sour limes and one sweet lime species. These limes often go by several different names, and each species has several different cultivars within the species.
Citrus aurantifolia is the most popular type of sour lime. This lime is more commonly called the Mexican or Key lime. The cultivars of this lime species are most of the limes you see in the supermarket. Citrus latifolia is more commonly called the Tahiti lime. It is far less common than C. aurantifolia, and its origins are unknown by scientists, according to Purdue University. Citrus limettioides is a sweet lime that is often confused with the sweet lemon.
Citrus aurantifolia is a shrubby tree that varies from 6 feet to more than 13 feet tall. This thorny but hardy tree features small, fragrant white flowers and even more fragrant leathery, dark-green, ovate leaves. The limes are ovate or round and light green to yellow, depending on the variety. They may have smooth or rough skin. Citrus latifolia and Citrus limettioides look alike. They are larger trees, reaching up to 20 feet tall, with long, drooping branches and no thorns. The flowers are white with a purple tinge, and the leaves are round, serrated and broad. The fruit is bright green until ripe, when it turns yellow, and has smooth skin.
Limes all have the same basic needs. They are adaptable when it comes to soil conditions, as long as the soil is loose and well-draining. These trees grow best in warm, protected climates, as they cannot tolerate freezing conditions, although the Tahiti lime can tolerate cold temperatures better than the Mexican lime. They prefer consistently moist soil and humid conditions.
Lime trees can suffer from fungal diseases, especially because they prefer humid weather. Allowing air to circulate around individual trees can prevent fungal problems such as leaf spot and powdery mildew. A systematic fungicidal treatment can also prevent diseases. Lime athracnose is a serious disease of the Mexican lime in Florida that causes young trees to wilt and die, and older trees to experience twig dieback. It is untreatable.
The Mexican lime has only a few cultivars. "Yung" was created to be thornless. "Everglade" produces fruit of an extremely high quality but is susceptible to anthracnose. Tahiti lime cultivars include the seedless "Bearss" and "USDA No. 1 and No. 2, which have fruit that is not any different from the true species but is much more disease-resistant. The sweet lime has two main varieties: "Soh Synteng," which has pinkish flowers and fruit with high acidity, and "Indian," which are hardy trees that produce juicy, bland fruit.