a subclass of dicotyledonous plants embracing families whose representatives have flowers with a calyx and corolla of free, or nonconcresced, petals (for example, Cruciferae and Rosaceae) and families whose representatives have no perianth (Piperaceae and Casuarinaceae) or have a simple perianth that is not divided into a calyx and a corolla.
This conception of Choripetalae was proposed in 1876 by the German botanist A. Eichler. In 1892 the German taxonomist A. Engler proposed the term Archichlamydeae for Choripetalae, because he considered separate petals as characteristics of primordial, more ancient dicotyledons. Less commonly, the term “Choripetalae” is applied only to those families of archichlamydeous plants that have a double perianth with free petals of the corolla, and they are separated into a special group Dialypetalae (Austrian botanist S. Endlicher, 1839); families with flowers having a homogeneous perianth or lacking one are classified in the group Monochlamydeae.
The classification of Choripetalae as a special subclass (juxtaposed to Sympetalae) is rejected by most botanists, because it has been proved that during the development of dicotyledons sympetaly arose in various groups of plants.
M. E. KIRPICHNIKOV