The almond (Prunus amygdalus, syn. Prunus dulcis) is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genus Prunus, it is classified with the peach 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 food cuisines, often featuring prominently in desserts, such as marzipan. The almond tree prospers in a moderate Mediterranean climate with cool winter weather. 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. Description The almond is a deciduous tree growing to in height, with a trunk of up to in diameter. The young twigs are green at first, becoming purplish where exposed to sunlight, then gray in their second year. The leaves are long, with a serrated margin and a petiole. The flowers are white to pale pink, 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 and the tree buds have a chilling requirement of 200 to 700 hours below 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 long. It is not a nut but a drupe. The outer covering, consisting of an outer exocarp, or