Crab apple (genus Malus) is a deciduous tree that differs from the orchard apple in bearing smaller, often acidic or astringent fruits. It is grown for its special Ornamental attributes (eg, tree form, showy blossoms, colour of fruit and sometimes leaves) and climatic adaptability. The fruits are valued for their superior jelly-making properties and as preserves. Many crab apples will intercross with sweet apples. In Canada, M. baccata, the Siberian crab apple, has been used to improve winter hardiness, and some prairie-hardy apple cultivars (cultivated varieties) have resulted. The Japanese flowering crab, M. floribunda, has also been used in traditional breeding, but as a source of resistance to the disease apple scab (Venturia inaequalis). Because of their long flowering period and abundant pollen, some types of crab apple are used in commercial apple orchards as pollen providers for the main cultivar. Approximately 9 species of crab apples are native to North America, mostly east of the Rocky Mountains, with only one, M. fusca (Oregon or Pacific crab), being native to British Columbia.