They are shrubs or small trees, mostly growing to 5-15 m tall, with small pome fruit and (usually) thorny branches. The most common type of bark is smooth grey in young individuals, developing shallow longitudinal fissures with narrow ridges in older trees. The fruits are sometimes known as "haws". The thorns are small sharp-tipped branches that arise either from other branches or from the trunk, and are typically 1-3 cm long (recorded as up to 11.5 cm in one casepage 97). The leaves grow spirally arranged on long shoots, and in clusters on spur shoots on the branches or twigs. The leaves of most species have lobed or serrate margins and are somewhat variable in shape.