A subclass of the. * Angiospermae containing all the flowering plants having embryos with two cotyledons. Its members usually possess a cambium and may thus be either woody or herbaceous. Other general features that can often be used to distinguish the Dicotyledonae from the * Monocotyledonae include: having broad leaves with branching veins; having flower parts inserted in fours or fives; having a persistent primary root that develops into a taproot; and having the vascular bundles in a ring (see eustele ). The Dicotyledonae contains about 250 families, ranging from the primitive Magnoliaceae to the advanced Composi-tae. In some classifications, dicotyledons are placed in the class Magnoliopsida. This is divided into some six or seven subclasses in recent classifications (see Magnoliidae, Hamamelidae, Caryophyl-lidae, Dilleniidae, Rosidae, Asteridae). In certain other classifications the Dilleniidae, the Rosidae, and sometimes also the Asteridae are grouped together. |
