 All except "Vauquelinia" (with 15 chromosomes) have a basal haploid chromosome count of 17, instead of 7, 8, or 9 as in the other Rosaceae.There are approximately 28 genera that contain about 1100 species worldwide, with most species occurring in the temperate Northern Hemisphere.The name Maleae is required by the International Code of Nomenclature for algae, fungi, and plants (article 19), for any group at the tribal level that includes the genus "Malus", but not either of the genera "Rosa" or "Amygdalus".