Avocado (Persea americana) is a tree and the fruit of that tree, classified in the flowering plant
family, Lauraceae. It is native to Central America and Mexico. The tree grows to 20 m (60 ft), with
alternately arranged, evergreen leaves,
12-25 cm long. The flowers are inconspicuous, greenish-yellow, 5-10 mm wide. The
pear-shaped fruit is botanically a berry, from 7 to
20 cm long, and weighs between 100-1000 g. It has a large central seed, 3-5 cm in diameter.
An average avocado tree produces about 120 avocados annually. The fruit is sometimes called an avocado pear or
alligator pear, from its shape and green skin. The avocado tree does not tolerate freezing temperatures, and so can be
grown only in subtropical and tropical climates.
Barlow & Martin (2002) identify the avocado as a fruit adapted for ecological
relationship with large mammals, now extinct (as for example the South American herbivorous giant ground sloths or Gomphotheres). This fruit with its
mildly toxic pit, co-evolved with those extinct mammals to be swallowed whole and excreted in dung, ready to sprout. The
ecological partners have disappeared, and the avocado plant has not had time to evolve an alternative seed dispersal
technique.
Cultivation & uses
It was introduced to the U.S. state of California in the 19th century, where it has become
an extremely successful cash crop. In the United States 95% of the avocados grown
are grown in California, with 80% in San
Diego County. Fallbrook, California claims the
title of "Avocado Capital of the World", and hosts an annual Avocado Festival. There are about 24,000 ha of avocado plantations in California.
The fruit of horticultural cultivars range from more or less round to egg or
pear-shaped, typically the size of a temperate zone pear or larger, on the outside bright
green to green-brown (or almost black) in color, and high in fat. Though the fruit does have
a markedly higher fat content than most other fruit, most of the fat in avocados is monounsaturated fat, which is considered healthy in the human diet. Avocados have 60% more potassium than bananas.
While dozens of cultivars exist, two are particularly commonly available, 'Hass' (commonly misspelled 'Haas') and 'Florida'.
The former is the most common cultivar, with a dark rippled skin, and rich, creamy flesh, accounting for more than 80% of the
crop grown in California. There are several other cultivars related to 'Hass', including 'Bacon', 'Fuerte' (pictured), 'Gwen',
'Pinkerton', 'Reed', and 'Zutano'. The cultivar 'Florida', grown mostly outside of California, is larger and rounder, with a
smooth, medium-green skin, and a less fatty, firmer and fibrous flesh. These are occasionally marketed as low-calorie
avocados.
The flesh is typically greenish yellow to golden yellow when ripe. The flesh oxidizes and turns brown quickly after exposure to air. To prevent this, a highly acidic juice like lime or lemon juice can be added to
avocados after they are peeled. The avocado is very popular in vegetarian cuisine, making a good substitute for meats and cheeses in sandwiches and salads because of
the high fat content. The fruit is not sweet, but fatty, flavorful, and of smooth, almost creamy texture. It is used as the base
for the Mexican dip known as guacamole, as well as a filling for several kinds of sushi, including
California rolls. In Brazil, avocados are added to ice cream and in the Philippines, a dessert drink is made
with sugar, milk, and pureed avocado.
The name "avocado" is from its Nahuatl name 'ahuacatl' which
also meant testicles, with influence from the irrelevant but much more familiar
Spanish avocado an obsolete form of 'abogado' (lawyer). In some countries of South America the avocado fruit is known as
'palta', which is a name that comes from the Quechua language. The Nahuatl
ahuacatl could be compounded with others, as in ahuacamolli, meaning "avocado soup or sauce", from which the
Mexican Spanish word guacamole derives. The plural of avocado is avocados or avocadoes.
The avocado fruit does not ripen on the tree, but will fall off (and must be picked up) in a hard, "green" state, then it will
ripen quickly on the ground, but depending of the amount of oil that it has the taste may be very different. Generally, the fruit
is picked once it reaches a mature size, and will then ripen in a few days (faster if stored with other fruit such as bananas, because of the influence of ethylene
gas). The fruit can be left on the tree until required, rather than picked and stored, but for commercial reasons it must be
picked up as soon as possible.
Avocado as a houseplant
Avocado can be grown as a houseplant from seed, although it will not normally bear fruit indoors, people enjoy it for its
greenery. It can be geminated in normal soil in a large pot, or in a glass of water with a piece of charcoal for deodourising,
with the top half held up by toothpicks.
References
- Barlow, Connie and Paul Martin. (2002) The Ghosts of Evolution: nonsensical fruit, missing partners and other ecological
anachronisms.
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