Ode to the Pistachio
The pistachio (Pistacia vera) is a small tree native to some regions of Syria, Iran, Turkey, Greece, Turkmenistan, Pakistan, and possibly Afghanistan, that produces an important culinary nut. The word pistachio is a loanword from Persian word Peste via Latin.
History
The modern pistachio nut P. vera was first cultivated in Western Asia, where it has long been an important crop in cooler parts of Iran. It appears in Dioscurides as pistakia, recognizable as P. vera by its comparison to pine nuts. Its cultivation spread into the Mediterranean world by way of Syria: Pliny in his Natural History asserts that pistacia, "well known among us", was one of the trees unique to Syria, and in another place, that the nut was introduced into Italy by the Roman consul in Syria, Lucius Vitellius the Elder (consul in Syria in 35CE) and into Hispania at the same time by Flaccus Pompeius. The early 6th-century manuscript De observatione ciborum (On the observance of foods) by Anthimus implies that pistacia remained well known in Europe in Late Antiquity.
Did you know?
Each pistachio tree averages around 50 kg of seeds, or around 50,000, every two years.
Biology
The bush grows up to 10 meters (30 ft) tall. It has deciduous pinnate leaves 10–20 centimeters (4–8 inches) long.
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 (14°F) in winter and 40°C (104°F) 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 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 (see photo). 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.