The almond (Prunus amygdalus, syn. Prunus dulcis) is a species of small tree from the genus Prunus, cultivated worldwide for its seed, a culinary nut. Along with the peach, it is classified in the subgenus Amygdalus, distinguished from the other subgenera by corrugations on the 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. 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. Once almonds are cleaned and processed, they can be stored over time. Almonds are used in many cuisines, often featuring prominently in desserts, such as marzipan.
The almond tree prospers in a moderate Mediterranean climate with cool winter weather. Native to Iran and surrounding countries including the Levant, today it is rarely found wild in its original setting. Almonds were one of the earliest domesticated fruit trees, due to the ability to produce quality offspring entirely from seed, without using suckers and cuttings. Evidence of domesticated almonds in the Early Bronze Age has been found in the archeological sites of the Middle East, and subsequently across the Mediterranean region and similar arid climates with cool winters.
California produces over half of the world's almond supply. Due to high acreage and water demand for almond cultivation, and need for pesticides, California almond production may be unsustainable, especially during the persistent drought and heat from climate change in the 21st century. Droughts in California have caused some producers to leave the industry, leading to lower supply and increased prices.
The almond is a deciduous tree growing to 4–12.2 metres (13–40 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 gray in their second year. The leaves are 8–13 cm (3–5 in) long,[9] 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 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, gray-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.