Persea is a genus of about 150 species of evergreen trees belonging to the laurel family, Lauraceae. The best-known member of the genus is the avocado, P. americana, widely cultivated in subtropical regions for its large, edible fruit. Overview They are medium-size trees, tall at maturity. The leaves are simple, lanceolate to broad lanceolate, varying with species from long and broad, and arranged spirally or alternately on the stems. The flowers are in short panicles, with six small greenish-yellow perianth segments long, nine stamens and an ovary with a single embryo. The fruit is an oval or pear-shaped berry, with a fleshy outer covering surrounding the single seed; size is very variable among the species, from in e.g. P. borbonia and P. indica, up to in some cultivars of P. americana. Distribution and ecology The species of Persea have a disjunct distribution, with about 70 Neotropical species, ranging from Brazil and Chile in South America to Central America and Mexico, the Caribbean, and the southeastern United States; a single species, P. indica, endemic to Madeira and the Canary Islands off northwest Africa; and 80 species inhabiting east and southeast Asia. None of the species are very tolerant of severe winter cold, with the hardiest, P. borbonia, P. ichangensis and P. lingue, surviving temperatures down to about ; they also require continuously moist soil, and do not tolerate drought. A number of these species are found in forests that face threats of destruction or deforestation; for example, P. meyeniana in Central Chile. The family Lauraceae was part of the land flora of Gondwana, and many genera had migrated to South America via Antarctica over ocean landbridges by the time of the Paleocene. From South America they spread over most of the continent. When the North American and South American tectonic plates joined in the late Neogene, volcanic mountain building created island chains which later formed the Mesoamerican landbridge. Pliocene elevation created new habitats for speciation. While some genera died out in increasingly xerophytic mainland Africa, starting with the freezing of Antarctica about 20 million years ago and the formation of the Benguela current, others, which also reached South America and Mesoamerica, such as Beilschmiedia and Nectandra are still surviving today in Africa in a number of species. The genus, however, died out in Africa, except for P. indica, which is, today, a threatened species that survives in the fog-shrouded mountains of