mandorla (アーモンド)

The almond is a deciduous tree growing to 3–4.5 metres (10–15 feet) in height, with a trunk of up to 30 centimetres (12 inches) in diameter. The young twigs are green at first, becoming purplish where exposed to sunlight, then grey in their second year. The leaves are 8–13 cm (3–5 in) long, with a serrated margin and a 2.5 cm (1 in) petiole.
The fragrant 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 trees thrive 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 200 to 700 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 is 3.5–6 cm (1+3⁄8–2+3⁄8 in) long. It is not a nut but a drupe. The outer covering, consisting of an outer exocarp, or skin, and mesocarp, or flesh, 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 woody endocarp which forms a reticulated, hard shell (like the outside of a peach pit) called the pyrena. Inside the shell is the edible seed, commonly called a nut. Generally, one seed is present, but occasionally two occur. After the fruit matures, the hull splits and separates from the shell, and an abscission layer forms between the stem and the fruit so that the fruit can fall from the tree. During harvest, mechanised tree shakers are used to expedite fruits falling to…

Scientific name
The almond was named Amygdalus communis by Carl Linnaeus in his Species plantarum in 1753. For the name 'Amygdalus' he referred to Gaspard Bauhin's Pinax (1623). In 1801 the species was for the first time placed in the genus Prunus by August Batsch. In that genus, the name Prunus communis was no longer available because in 1778 William Hudson had already assigned it to a taxon in which he included the plum (Prunus domestica). Batsch thereupon named the species Prunus amygdalus, where 'amygdalus' is the old generic name and should therefore be treated as a noun in apposition. Meanwhile, in 1768, Philip Miller had published the name of what he believed to be a second species of almond: Amygdalus dulcis. He mentioned Linnaeus' Amygdalus communis as the first species. It was not until 1967 that the combination Prunus dulcis was published for the almond by David Allardice Webb, on the assumption that Amygdalus dulcis was nothing more than a synonym of Amygdalus communis, and thus an available name for that species. The epithet dulcis (1768) is older than amygdalus (1801) and would therefore have priority. Webb noted that it was unfortunate that a species known for 165 years as Prunus amygdalus now had to be renamed under the rules of nomenclature. However, it later turned out that in 1967 the name Prunus dulcis was no longer available for the almond because it had already been used for a cherry in an 1878 publication by L'Abbé Rouchy. The oldest valid combination in Prunus is therefore Prunus amygdalus.

Sweet and bitter almonds

The seeds of Prunus amygdalus 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 being…

The precise origin of the almond is controversial due to estimates for its emergence across wide geographic regions. Sources indicate that its origins were in an area stretching across Central Asia, Iran, Turkmenistan, Tajikistan, Kurdistan, Afghanistan, and Iraq, or in an eastern Asian subregion between Mongolia and Uzbekistan. In other assessments, both botanical and archaeological evidence indicates that almonds originated and were first cultivated in West Asia, particularly in countries of the Levant. Most recent sources specified Iran and Anatolia (present day Turkey) as origin locations of the almond, with Iran as the main origin centre.
The wild form of domesticated almond grew in parts of the Levant. Almond cultivation was spread by humans centuries ago along the shores of the Mediterranean Sea into northern Africa and southern Europe, and more recently to other world regions, notably California.
Selection of the sweet type from the many bitter types in the wild marked the beginning of almond domestication. The wild ancestor of the almond used to breed the domesticated species is unknown. The species Prunus fenzliana may be the most likely wild ancestor of the almond, in part because it is native to Armenia and western Azerbaijan, where it was apparently domesticated. Wild almond species were grown by early farmers, "at first unintentionally in the garbage heaps, and later intentionally in their orchards".

Almonds were one of the earliest domesticated fruit trees owing to their ability to be grown from seed, allowing their cultivation to have perhaps predated the advent of grafting.
Domesticated almonds appear in the Early Bronze Age (3000–2000 BCE), such as the archaeological sites of Numeira (Jordan), or possibly earlier. They were found in Tutankhamun's tomb in Egypt (c. 1325 BCE), probably imported from the Levant.
Ibn al-'Awwam's 12th-century Book on Agriculture includes an article on almond tree cultivation in Spain.
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.

Varieties
Almond trees are small to medium-sized but commercial cultivars can be grafted onto a different root-stock to produce smaller trees. Varieties include:

Nonpareil – originates in the 1800s. A large tree that produces large, smooth, thin-shelled almonds with 60–65% edible kernel per nut. Requires pollination from other almond varieties for good nut production.
Tuono – originates in Italy. Has thicker, hairier shells with only 32% of edible kernel per nut. The thicker shell gives some protection from pests such as the navel orangeworm. Does not require pollination by other almond varieties.
Mariana – used as a rootstock to result in smaller trees
Breeding programs have found a high shell-seal trait, which reduces insect damage and mold contamination.

Pollination
The most widely planted varieties of almond are self-incompatible; hence these trees require pollen from a tree with different genetic characters to produce seeds. Almond orchards therefore must grow mixtures of almond varieties. In addition, the pollen is transferred from flower to flower by…