Persea americana, avocado, is a tropical, frost-intolerant evergreen tree in the Lauraceae (laurel family) that originated in central America and is now cultivated in tropical and semitropical areas worldwide for its oil-rich fruit. Avocados, which have been used by humans for at least 8,000 years, as recorded in archaological finds in Mexico and Peru (it was cultivated from the Rio Grande to central Peru before Europeans arrived), are often referred to as the most nutritious of all fruits, with high amounts of vitamins B (riboflavin, niacin, folate and pantothenic acid), C, and E, as well as the minerals potassium and copper, are often used in salads or in the typical Latin American dish, guacamole—mashed avocado with spices, which may be of Aztec origin.
The avocado tree typically grows to 9 or 10 m (28 to 32 ft) tall, but may grow to 18 m (60 ft) or more, with a trunk 30 to 60 cm (12 to 24 in) in diameter. The leaves are thick, glossy, dark green above and paler below, and are briefly shed around the time of flowering. Leaf shape is variable, ranging from oval to elliptical to lanceolate, with a bluntly pointed tip (acute) or narrowing to a pointed (acuminate); the leaves may be anywhere from 7.5 to 40 cm (3 to 16 in) long. The small yellowish to greenish insect-pollinated flowers are borne in many-flowered clusters either terminal or near the branch tips. The fruits are pear-shaped, oval, or nearly globe-shaped, 7.5 to 33 cm long (3 to 13 in) and up to 15 cm (6 in) wide, with a tough, leathery rind that at maturity ranges in color from yellow-green to dark green to purple to almost black, and may be smooth or pebbly in texture. The flesh is creamy smooth, sometimes pale to golden yellow or green, enclosing a single large round to conical seed, 5 to 6.4 cm (2 to 2.5 in) long. The creamy flesh is edible, but the seeds and skin, as well as the leaves of the tree, are toxic to many domestic animals.
The U.N. Food and Agriculture Organization (FAO) estimates that the total commercial production of avocados was 3.8 million metric tons in 2010, harvested from 459,252 hectares worldwide. Mexico was the leading producer, responsible for 29% of the total. Other major producers include Chile, Dominican Republic, Indonesia, and Columbia. The U.S. ranked 8th, although for many years it was one of the top producers (in 2006 it ranked 3rd). Within the U.S., avocados are cultivated in California, Florida, and Hawaii.
Avocados have been referred to as an “ecological anachronism,” because they now lack animal dispersers for their seeds. Research suggests that in past millennia, the fruits were eaten by various large mammals that are now extinct in Central America, including the mastodon-like gomphotheres, giant ground sloths, and various equid species. Avocado seed germination benefits from passage through an animal gut, and dispersal is necessary so that the large heavy fruits don’t simply fall in the shade of the parent tree, where existing competition will impede seedling survival and growth.
(Bailey et al. 1976, Barlow 2000, FAOSTAT 2012, Janzen and Martin 1982, Morton 1987, USDA 2006, van Wyk 2005.)
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