Embryo containing 2 or more (rarely 1) cotyledons, opposite or in a whorl. Leaves net-veined. Stem perennial, with pith, wood, and bark; with medullary rays, and increased by rings of wood on the outside yearly. Perianth of 4 or 5 or 2 divisions.

Sub-Class I. - Polypetalae

Perianth of 2 whorls, calyx and corolla; petals distinct as a rule.