Pistachio

Appearance

The bush grows up to 10 metres tall. It has deciduous pinnate leaves 10–20 centimeters 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, which is the edible portion. The seed, commonly thought of as a nut, is a culinary nut, not a botanical nut. The fruit has a hard, whitish exterior shell. The seed has a mauvish skin and light green flesh, with a distinctive flavor. When the fruit ripens, the shell changes from green to an autumnal yellow/red, and abruptly splits part way open . This is known as dehiscence, and happens with an audible pop. The splitting open is a trait that has been selected by humans. Commercial cultivars vary in how consistently they split open.

Each pistachio tree averages around 50 kg of seeds, or around 50,000, every two years.

The shell of the pistachio is naturally a beige color, but it is sometimes dyed red or green in commercial pistachios. Originally, dye was applied by importers to hide stains on the shells caused when the seeds were picked by hand. Most pistachios are now picked by machine and the shells remain unstained, making dyeing unnecessary except to meet ingrained consumer expectations. Roasted pistachio seeds can be artificially turned red if they are marinated prior to roasting in a salt and strawberry marinade, or salt and citrus salts.

Like other members of the Anacardiaceae family , pistachios contain urushiol, an irritant that can cause allergic reactions.

Habitat

Pistachio is a desert plant, and is highly tolerant of saline soil. It has been reported to grow well when irrigated with water having 3,000–4,000 ppm of soluble salts. Pistachio trees are fairly hardy in the right conditions, and can survive temperatures ranging between −10 °C in winter and 48 °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.

The Jylgyndy Forest Reserve, a preserve protecting the native habitat of ''Pistacia vera'' groves, is located in the Nooken District of Jalal-Abad Province of Kyrgyzstan.

Evolution

Archaeologists have found evidence from excavations at Jarmo in northeastern Iraq
that pistachio seeds were a common food as early as 6750 BC. The Hanging Gardens of Babylon were said to have contained pistachio trees during the reign of King Merodach-Baladan about 700 BC. The modern pistachio ''P. vera'' was first cultivated in Western Asia, where it has long been an important crop in cooler parts of Iran and Iraq. It appears in Dioscurides as ''pistakia'' πιστάκια, recognizable as ''P. vera'' by its comparison to pine nuts. Its cultivation spread into the Mediterranean world by way of Persia from Syria.

Additionally, remains of the Atlantic pistachio and pistachio seed along with nut-cracking tools were discovered by archaeologists at the Gesher Benot Ya'aqov site in Israel's Hula Valley, dated to 780,000 years ago.

Pliny in his ''Natural History'' asserts that ''pistacia'', “well known among us,” was one of the trees unique to Syria, and that the seed was introduced into Italy by the Roman consul in Syria, Lucius Vitellius the Elder and into Hispania at the same time by Flaccus Pompeius. The early sixth-century manuscript ''De observatione ciborum'' by Anthimus implies that ''pistacia'' remained well known in Europe in Late Antiquity. The pistachio is one of three seeds mentioned in the Bible. The pistachio is mentioned once, in , as is the walnut in , while the almond is mentioned many times.

More recently, the pistachio has been cultivated commercially in many parts of the English-speaking world, in Australia, and in New Mexico and California, of the United States, where it was introduced in 1854 as a garden tree. David Fairchild of the United States Department of Agriculture introduced hardier cultivars collected in China to California in 1904 and 1905, but it was not promoted as a commercial crop until 1929. Walter T. Swingle’s pistachios from Syria had already fruited well at Niles by 1917.

The earliest records of pistachio in English are around roughly year 1400, with the spellings “pistace” and “pistacia”. The word pistachio comes from medieval Italian ''pistacchio'', which is from classical Latin ''pistacium'', which is from ancient Greek ''pistákion'' and ''pistákē'', which is generally believed to be from Middle Persian, although unattested in Middle Persian. Later in Persian, the word is attested in Persian as ''pista''. As mentioned, the tree came to the ancient Greeks from Western Asia.