The almond (Prunus dulcis, syn. Prunus amygdalus) is a species of tree native to the Middle East, the Indian Subcontinent andNorth Africa.
"Almond" is also the name of the edible and widely cultivated seed of this tree. Within the genus Prunus, it is classified with thepeach in the subgenus Amygdalus, distinguished from the other subgenera by the corrugated shell (endocarp) surrounding the seed.
The fruit of the almond is a drupe, consisting of an outer hull and a hard shell with the seed, which is not a true nut, inside. Shelling almonds refers to removing the shell to reveal the seed. Almonds are sold shelled or unshelled. Blanched almonds are shelled almonds that have been treated with hot water to soften the seedcoat, which is then removed to reveal the white embryo.
The almond is a deciduous tree, growing 4–10 m (13–33 ft) in height, with a trunk of up to 30 cm (12 in) in diameter. The youngtwigs are green at first, becoming purplish where exposed to sunlight, then grey in their second year. The leaves are 3–5 inches long, with a serrated margin and a 2.5 cm (1 in) petiole. The flowers are white to pale pink, 3–5 cm (1–2 in) diameter with five petals, produced singly or in pairs and appearing before the leaves in early spring. Almond grows best in Mediterranean climates with warm, dry summers and mild, wet winters. The optimal temperature for their growth is between 15 and 30 °C (59 and 86 °F) and the tree buds have a chilling requirement of 300 to 600 hours below 7.2 °C (45.0 °F) to break dormancy.
Almonds begin bearing an economic crop in the third year after planting. Trees reach full bearing five to six years after planting. The fruit matures in the autumn, 7–8 months after flowering.
The almond fruit measures 3.5–6 cm (1–2 in) long. In botanical terms, it is not a nut, but a drupe. The outer covering orexocarp, fleshy in other members of Prunus such as the plum and cherry, is instead a thick, leathery, grey-green coat (with a downy exterior), called the hull. Inside the hull is a reticulated, hard, woody shell (like the outside of a peach pit) called the endocarp. Inside the shell is the edible seed, commonly called a nut. Generally, one seed is present, but occasionally two occur.
Origin and history
Harvesting of the almond crop at Qand-i Badam,Fergana Valley (16th century)
The almond is native to the Mediterranean climate region of the Middle East, eastward as far as the Yamuna River in India. In Iran, India, Afghanistan, Azerbaijan and other Central Asian countries, it is known as b?d?m. It was spread by humans in ancient times along the shores of the Mediterranean into northern Africa and southern Europe, and more recently transported to other parts of the world, notably California, United States.
The wild form of domesticated almond grows in parts of the Levant. The fruit of the wild forms contains the glycoside amygdalin, "which becomes transformed into deadly prussic acid (hydrogen cyanide) after crushing, chewing, or any other injury to the seed."
Wild almonds are bitter, the kernel produces deadly cyanide upon mechanical handling[clarification needed], and eating even a few dozen in one sitting can be fatal. Selection of the sweet type, from the many bitter types in wild, marked the beginning of almond domestication. How humans selected the sweet type remains a mystery. It is unclear as to which wild ancestor of the almond created the domesticated species. Ladizinsky suggests the taxon Amygdalus fenzliana (Fritsch) Lipsky is the most likely wild ancestor of the almond in part because it is native of Armenia and western Azerbaijan where it was apparently domesticated.
While wild almond species are toxic, domesticated almonds are not; Jared Diamond argues that a common genetic mutation causes an absence of amygdalin, and this mutant was grown by early farmers, "at first unintentionally in the garbage heaps, and later intentionally in their orchards". Zohary and Hopf believe that almonds were one of the earliest domesticated fruit trees due to "the ability of the grower to raise attractive almonds from seed. Thus, in spite of the fact that this plant does not lend itself to propagation from suckers or from cuttings, it could have been domesticated even before the introduction of grafting". Domesticated almonds appear in the Early Bronze Age (3000–2000 BC) such as the archaeological sites of Numeria (Jordan), or possibly a little earlier. Another well-known archaeological example of the almond is the fruit found in Tutankhamun's tomb in Egypt (c. 1325 BC), probably imported from the Levant. Of the European countries that the Royal Botanic Garden Edinburgh reported as cultivating almonds, Germany is the northernmost, though the domesticated form can be found as far north as Iceland.
Etymology and names
The word "almond" comes from Old French almande or alemande, Late Latin *amandula, derived through a form amygdala from the Greek ???????? (amygdal?) (cf.amygdala), an almond. The al- in English, for the a- used in other languages may be due a confusion with the Arabic article al, the word having first dropped the a-as in the Italian form mandorla; the British pronunciation ah-mond and the modern Catalan ametlla and modern French amande show a form of the word closer to the original. Other related names of almond include Mandel or Knackmandel (German), mandorlo (Italian for the tree), mandorla (Italian for the fruit), amêndoa(Portuguese), and almendra (Spanish).
The adjective "amygdaloid" (literally "like an almond") is used to describe objects which are roughly almond-shaped, particularly a shape which is part way between atriangle and an ellipse. See, for example, the brain structure amygdala, which uses a direct borrowing of the Greek term amygdal?.
World production of almonds was 2.9 million tonnes in 2013, with United States as the largest producer of 1.8 million tonnes.
|Top producers of almonds (with shell) in 2013
In the United States, production is concentrated in California, with almonds being California's third-leading agricultural product, its top agricultural export in 2008, and 100% of the U.S. commercial supply. The United States is the dominant supplier of almonds. Almonds are mostly exported as shelled almonds (70%), with the remainder being either unshelled or processed. In 2015, environmental problems in California affected the almond supply, contributing to higher almond prices worldwide. Rising demand for almonds has also contributed to higher prices worldwide and increased production in California.
Australia is the largest almond production region in the Southern Hemisphere, and second largest producing country. In 2013, Australia produced 9% of the world almond supply (table). Most of the almond orchards are located along the Murray River corridor in New South Wales, Victoria, and South Australia.
Spain has one of the most diverse commercial cultivars of almonds. It is grown in Spain's Catalonia, Valencia, Murcia, Andalusia, and Aragón regions and the Balearic Islands. In Greece, most of the production comes from the region of Magnesia at the area of Almyros. The most cultivated types of almonds in Greece are 'Ferragnes' and 'Texas' ('Mission'), which are known for their sweet taste and premium quality. Because of its quality, it is used as a luxury nut. In Turkey, most of the production comes from the Aegean, Marmara, and Mediterranean regions.
The pollination of California's almonds is the largest annual managed pollination event in the world, with close to one million hives (nearly half of all beehives in the USA) being trucked in February to the almond groves. Much of the pollination is managed by pollination brokers, who contract with migratorybeekeepers from at least 49 states for the event. This business has been heavily affected by colony collapse disorder, causing nationwide shortages of honey bees and increasing the price of insect pollination. To partially protect almond growers from the rising cost of insect pollination, researchers at the Agricultural Research Service (ARS) have developed a new line of self-pollinating almond trees.Self-pollinating almond trees, such as the 'Tuono', have been around for a while, but their harvest is not as desirable as the insect-pollinated California 'Nonpareil' almond tree. The 'Nonpareil' tree produces large, smooth almonds and offers 60–65% edible kernel per nut. The 'Tuono' has thicker, hairier shells and offers only 32% of edible kernel per nut, but having a thick shell has advantages. The 'Tuono's' shell protects the nut from threatening pests such as the navel orangeworm. ARS researchers have managed to crossbreed the pest-resistant 'Tuono' tree with the 'Nonpareil', resulting in hybridized varieties of almond trees that are self-pollinated and maintain a high nut quality. The new, self-pollinating hybrids possess quality skin color, flavor, and oil content, and reduce almond growers' dependency on insect pollination.
Main article: List of almond diseases
Almond trees can be attacked by an array of damaging organisms, including insects, fungal pathogens, plant viruses, and bacteria.
Sweet and bitter almonds
Flowering (sweet) almond tree
Blossom on bitter almond tree
The seeds of Prunus dulcis var. dulcis are predominantly sweet, but some individual trees produce seeds that are somewhat more bitter. The genetic basis for bitterness involves a single gene, the bitter flavour furthermore beingrecessive, both aspects makin