The Maloideae are the apple subfamily, a grouping traditionally used by some taxonomists within the rose family, Rosaceae. Approximately 28 genera have been included by various authors, including approximately 1100 species worldwide, with most species occurring in the temperate Northern Hemisphere. The group includes a number of plants bearing commercially important fruits, such as apples and pears, while others are cultivated as ornamentals.
In its traditional circumscription this subfamily consisted exclusively of shrubs and small trees characterised by a pome, a type of accessory fruit that does not occur in non-Maloid Rosaceae, and by a basal haploid chromosome count of 17 (instead of 7, 8, or 9 as in the other subfamilies). The syncarpous flowers have one to five carpels which are at least partly fused to each other and to the hypanthium (floral cup), making the ovary at least three-quarters inferior, though it is said that the flowers in the genera Cotoneaster, Heteromeles, and Pyracantha are completely apocarpous, i.e. with carpels free from each other. The hypanthium with the ovaries matures into the pome fruit. The leaves of the plants in this group are evergreen or deciduous. These leaves come in a wide variety of shapes from simple leaves with entire, toothed or pinnately lobed margins to pinnately compound leaves. They can be thin (membranaceous) or with a leathery texture (coriaceous).
The subfamily was earlier known as Pomoideae, a name that is no longer accepted under the International Code of Botanical Nomenclature. It has also been separated into its own family the Malaceae or Pomaceae.
Recent molecular data have shown that subfamily Maloideae evolved from within subfamily Spiraeoideae, as did the traditional subfamily Prunoideae, and to best reflect relationships subfamily Spiraeoideae has been expanded. With this classification the traditional Maloideae are considered to be part of Spiraeoideae. An earlier intermediate classification expanded Maloideae to include four genera with dry non-pome fruit. These are Kageneckia, Lindleya, and Vauquelinia, which have a haploid chromosome count of 15 or 17, and Gillenia, which is herbaceous and has a haploid chromosome count of 9.
Full article ▸