Pistachio

? Pistachio
Pistachio with ripening fruit
Plant Info
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Sapindales Family: Anacardiaceae Genus: Pistacia Species: P. vera
Binomial name
Pistacia vera L.

The pistachio (Pistacia vera, Anacardiaceae; sometimes placed in Pistaciaceae) is a small tree up to 10 m tall, native to mountainous regions of central and southwestern Asia such as the Kopet Dag mountains of Turkmenistan southwest to northeastern Iran and western Afghanistan. It has deciduous pinnate leaves 10-20 cm long.

The plants are dioecious, with separate male and female trees. The flowers are apetalous and unisexual, and borne in panicles. The fruit is a drupe, containing an elongated seed (a nut in the culinary sense, but not a true botanical nut) with a hard, whitish shell and a striking light green kernel, having a very characteristic flavour.

When the fruit ripens, the shells split open partially (see photo). This happens with an audible pop, and legend has it that lovers who stand under a pistachio tree at night and hear the nuts popping open will have good luck.

History

Pistachio is often confused with some of the other nine species in the genus Pistacia, such as P. terebinthus and P. lentiscus. These species have a very different distribution, in the Mediterranean and southwest Asia, and have much smaller nuts, lacking the hard shell of P. vera. Their turpentine-flavoured nuts were a popular food in antiquity. Finds of Pistacia from pre-classical archaeological sites, or references in pre-classical texts, always refer to one of these other species (often P. terebinthus).

Pistachio (in the sense of P. vera) was presumably first cultivated in Central Asia. It reached the Mediterranean world by way of central Iran, where it has long been an important crop. Although known to the Romans, the pistachio nut appears not to have reached the Mediterranean or most of the Near East in any quantity before medieval times. More recently pistachio has been cultivated in California (first commercial harvest in 1976) and Australia. The word pistachio itself is perhaps a Middle Persian loanword into English and may be a cognate to the Modern Persian word پسته Pesteh.

Cultivation and uses

Pistachio nuts in the shell and out of it

The kernels are eaten whole, either fresh or roasted and salted, and are also used in ice cream and confections such as baklava.

The shell of the pistachio is naturally a beige colour, but it is sometimes dyed red or green in commercial pistachios. Originally the dye was applied by importers to hide stains on the shells caused when the nuts were picked by hand. However most pistachios are now picked by machine and the shells remain unstained, making dyeing unnecessary (except that some consumers have been led to expect colored pistachios). Roasted pistachio nuts turn naturally red if they are marinated before in a salt and strawberry marinade, or salt and citrus salts Template:Fact.

The trees are planted in orchards, and take approximately seven to ten years to reach significant production. Production is alternate bearing or biennial bearing, meaning the harvest is heavier in alternate years. Peak production is reached at approximately 20 years. Trees are usually pruned to size to make the harvest easier. One male tr ee produces enough pollen for eight to twelve nut-bearing females. Pistachio orchards can be damaged by the fungal disease Botryosphaeria panicle and shoot blight, which kills the flowers and young shoots.

Pistachio trees are fairly hardy in the right conditions, and can survive temperature ranges between -10°C in winter to 40°C in summer. They need a sunny position and well-drained soil. Pistachio trees do poorly in conditions of high humidity, and are susceptible to root rot in winter if they get too much water and the soil is not sufficiently free draining. Long hot summers are required for proper ripening of the fruit.

Pistachio nuts are highly flammable when stored in large quantities, and are prone to self heating and spontaneous combustion (see Cargo container's handbook).

Diseases

Main article: List of pistachio diseases

Worldwide production

Share of a total 2005 worldwide production of 501 thousand metric tonnes:

Country	Production Percentage
Iran	38%
U.S. (mainly California)	28%
Turkey	12%
Syria	12%
China	7%
Greece	2%
Rest of world	1%

Source: FAOSTAT [1]

California produces almost all U.S. pistachios, and about half of this is exported, mainly to China, Hong Kong, Japan, Europe and Canada. Almost all California pistachios are of the cultivar 'Kerman'. The tree is grafted to a rootstock when the rootstock is one year old.

References

• Germplasm Resources Information Network: Pistacia vera
• California Pistachio Commission
• Nutrition facts