Botany and taxonomy of pear

Pear belongs to the Rosaceae family as most of the cultivated fruit trees. It is the second fruit tree crop in terms of production after apple. Its production has increased these last decades to reach a world production of more than 27 megatons for almost 1,600,000 ha. Pears have been cultivated in Europe and in Asia for more than 5,000 years. Of all known and reported pear species and interspecific hybrids, five are mainly cultivated. These include the European pear, Pyrus communis, and the Asian pears P. pyrifolia, P. ×bretschneideri, P. ussuriensis, and P. sinkiangensis. Fruits of European pears are elongated and have a full-bodied texture, while those of Asian pears are round and have a sandy texture. The Pyrus genus belongs to the Amygdaloideae subfamily and the Malinae tribe, and consists of about 75 to 80 species and interspecific hybrid species. As several hybridizations are observed among Pyrus species, this renders the distinction among some pear species rather difficult. The origin of the Pyrus genus dates back to the Oligocene Epoch, about 33.35 to 25.23 Mya. It is a genus of mainly deciduous trees and shrubs spread throughout temperate Eurasia, reaching the Atlas Mountains in North Africa, and extending to Japan and South China. Pyrus species produce generally simple leaves alternately arranged. Leaves are glossy green on some species, densely silvery-hairy in some others. Pyrus flowers are white, borne in corymbs on short spurs or lateral branchlets, and are composed of five sepals, five petals, numerous stamens, and usually a five-locular ovary with free styles. The Pyrus fruit is a pseudo-fruit composed of the receptacle or the calyx tube, greatly dilated, enclosing the true fruit, and consisting of five cartilaginous carpels, known as the core. Morphological characters of the leaf, fruit, and calyx are commonly used to differentiate among Pyrus species. There are thousands of pear cultivars over the world with wide diversity for fruit shape, taste, and texture. In this chapter, we have focused on the description of cultivated Pyrus species and on some of the main cultivated cultivars