Cherry blossom

The cherry blossom, or sakura, is the flower of trees in Prunus subgenus Cerasus. Sakura usually refers to flowers of ornamental cherry trees, such as cultivars of Prunus serrulata, not trees grown for their fruit (although these also have blossoms). Cherry blossoms have been described as having a vanilla-like smell, which is mainly attributed to coumarin.

Wild species of cherry tree are widely distributed, mainly in the Northern Hemisphere. They are common in East Asia, especially in Japan, where they have been cultivated, producing many varieties.

Most of the ornamental cherry trees planted in parks and other places for viewing are cultivars developed for ornamental purposes from various wild species. In order to create a cultivar suitable for viewing, a wild species with characteristics suitable for viewing is needed. Prunus speciosa (Oshima cherry), which is endemic to Japan, produces many large flowers, is fragrant, easily mutates into double flowers and grows rapidly. As a result, various cultivars, known as the Cerasus Sato-zakura Group, have been produced since the 14th century and continue to contribute greatly to the development of hanami (flower viewing) culture. From the modern period, cultivars are mainly propagated by grafting, which quickly produces cherry trees with the same genetic characteristics as the original individuals, and which are excellent to look at.

The Japanese word sakura (桜; Japanese pronunciation: [sa.kɯ.ɾa]) can mean either the tree or its flowers (see 桜). The cherry blossom is considered the national flower of Japan, and is central to the custom of hanami.

Sakura trees are often called Japanese cherry in English. (This is also a common name for Prunus serrulata.) The cultivation of ornamental cherry trees began to spread in Europe and the United States in the early 20th century, particularly after Japan presented trees to the United States as a token of friendship in 1912. British plant collector Collingwood Ingram conducted important studies of Japanese cherry trees after the First World War.

Classifying cherry trees is often confusing, since they are relatively prone to mutation and have diverse flowers and characteristics, and many varieties (a sub-classification of species), hybrids between species, and cultivars exist. Researchers have assigned different scientific names to the same type of cherry tree throughout different periods.

In Europe and North America, ornamental cherry trees are classified under the subgenus Cerasus ("true cherries"), within the genus Prunus. Cerasus consists of about 100 species of cherry tree, but does not include bush cherries, bird cherries, or cherry laurels (other non-Cerasus species in Prunus are plums, peaches, apricots, and almonds). Cerasus was originally named as a genus in 1700 by de Tournefort. In 1753, Linnaeus combined it with several other groupings to form a larger Prunus genus. Cerasus was later converted into a section and then a subgenus, this system becoming widely accepted, but some botanists resurrected it as a genus instead. In China and Russia, where there are many more wild cherry species than in Europe, Cerasus continues to be used as a genus.

In Japan, ornamental cherry trees were traditionally classified in the genus Prunus, as in Europe and North America, but after a 1992 paper by Hideaki Ohba of the University of Tokyo, classification in the genus Cerasus became more common. This means that (for example) the scientific name Cerasus incisa is now used in Japan instead of Prunus incisa.