Apetalae

the name of a group of families of dicotyledonous plants that lack perianths, have only one rudimentary perianth (for example, the Salicaceae family), or have only a simple perianth—that is, a perianth not divided into a calyx and a corolla (for example, the Polygonaceae family).

The Apetalae group is usually placed at the beginning of the system of dicotyledonous plants and is considered more primitive than other groups. The term “Apetalae” has primarily a historical significance, since the Apetalae include families not related to one another. In the system of the German botanist A. Engler (adopted in the multivolume Flora of the USSR), Apetalae are included among the so-called Archichlamydeae, or choripetalous plants, but the majority of contemporary taxonomists reject this inclusion.