Persea is a genus in the laurel family that contains around 150 different species. These evergreens are angiosperms, which mean they produce flowers. They thrive in warm climates with adequate rainfall and well-drained, sandy soil.
The most well known varieties are avocados. There is evidence that Persea americano, an avocado tree endemic to Mexico, has been cultivated throughout Central and South America for several thousand years. Over time different varieties have developed in the West Indies and Guatemala. The West Indies variety produces a much larger fruit which is low in oil. These avocados have a shiny green covering and due to their size, can take up to 18 months to mature.
The Guatemalan and Mexican avocados are smaller and have knobby dark green or black shells. The fruit is rich in oil and contains less meat than the larger plants on the islands, but also matures faster. The fruit generally ripens within the year. Most avocados must be planted in warm areas which seldom encounter frost. The West Indies tree can be damaged if temperatures reach a freezing point while the Mexican and Guatemalan trees can tolerate somewhat colder temperatures.
Avocados have also been a part of African botanical history. The fruit is used in traditional medicine as an anticonvulsant for people suffering from epilepsy and other forms of seizures. Powder ground from the seed is being studied as a possible treatment for diabetes.
Persea borbonia, called the redbay after its beautiful red wood, is a non-fruit bearing species which grows in the southern United States. This hardwood is found in abundance along streams and in wooded areas in North Carolina, South Carolina, Georgia, Alabama, Florida, Arkansas, Louisiana, Mississippi and Texas. An invasion of beetles brought from Asia on shipping pallets has killed large sections of the tree in Georgia and threatens to make the redbay an endangered species.
The swamp redbay, Persae palustris, is a related tree found in swampy areas in the southern US, Mexico and the Bahamas. It is a medium size tree which reaches a maximum height of around 25 feet (7.62 m). It has bright green leaves that produce a pleasant smell when crushed and is used as a substitute for European bay leaves in cooking.
Over half of the Persea species are native to Asia. One of these, Persea yunnanensis, also known as the Chinese avocado, produces a blue fruit that is more like an olive than an avocado. It is taller than many avocados and can reach a height of 40 feet (12.19 m). The tree can grow in both sunny and shady areas and, once established, is fairly drought resistant. While not endemic to the Western hemisphere, it can occasionally be found in nurseries in warmer climates.
Persea macrantha, another Asian variety found in the mountain regions of India, is known for its folk medicinal value. The leaves are used to treat wounds, asthma, coughs and edema. The aromatic bark is also a popular resource for making incense sticks. The demand for these trees is exceeding the supply and in some areas of India it has been placed on an endangered list.