The most common species of bay tree is Laurus nobilis. Known as the sweet bay, bay laurel or Mediterranean bay, the hardy evergreen shrub originated in Asia Minor and was cultivated the Mediterranean region. The shrub grows in temperate climates around the world. The leaves of Laurus nobilis have a milder aroma and flavor than other bay leaf varieties.
The California bay laurel tree, Umbellularia californica, has many common names, such as laurel, myrtle and pepperwood. The tree grows in coastal forests in western North America and has dark gray-green, narrow, oval leaves with smooth edges. California bay leaves are stronger in aroma and flavor than those of the Mediterranean bay. In cooking, the California bay leaf can be used in the same manner as Mediterranean bay leaves, but in half the quantity. The strong aroma of California laurel trees causes some people to experience headaches.
Often confused with the more common Mediterranean bay, the Indian bay grows on the southern slopes of the Himalayan mountains, and is not available in the west. Known by the Latin name of Cinnamomum tamala, the tree is closely related to cinnamon. Indian bay leaves carry an odor reminiscent of cinnamon and cloves.
The West Indian bay tree, known by its Latin name as Pimenta racemosa, is used as a spice. Its oil is used as an ingredient in rum.The Mexican bay, Litsea glaucescens, is a less common species of bay tree that grows in Mexico and Central America. Its leaves can be used a substitute for Laurus nobilis. Under the family of Lauraceae, the genus of Litsea contains many varieties of aromatic shrubs whose leaves are often called bay leaves.