The flowers are borne in corymbs, and have five petals, which may be white, pink, or red, and are perfect, with usually red stamens that produce copious pollen, and a half-inferior ovary; flowering occurs in the spring after 50–80 growing degree days (varying greatly according to subspecies and cultivar).

[7] 36 species and four natural hybrids are accepted:[2] After[7] Crabapples are popular as compact ornamental trees, providing blossom in spring and colourful fruit in autumn.

[10][11][12] These cultivars have won the Royal Horticultural Society's Award of Garden Merit:[13] Other varieties are dealt with under their species names.

[22] Crabapple fruit is not an important crop in most areas, being extremely sour due to malic acid (which like the genus derives from the Latin name mālum), and in some species woody, so is rarely eaten raw.

In some Southeast Asian cultures, they are valued as a sour condiment, sometimes eaten with salt and chilli or shrimp paste.

Using sugar and spices such as ginger, nutmeg, cinnamon, and allspice, their juice can be made into ruby-coloured crab apple jelly with a full, spicy flavour.

[25] As Old English Wergulu, the crab apple is one of the nine plants invoked in the pagan Anglo-Saxon Nine Herbs Charm, recorded in the 10th century.