Class Magnoliopsida (Dicotyledons)

Embryo usually with two cotyledons, sometimes one, rarely with three or four. Cotyledons commonly with three vascular bundles. Leaves mostly petioled. Venation typically reticulate, either pinnate or palmate, and mostly not closed (with free vein endings). Leaf traces 1–3, seldom more. Prophylls and bracteoles are usually paired. Plumule terminal. Vascular bundles usually arranged in a ring, seldom in two or more rings or scattered. The root system mostly that of a tap root from which side branches arise. The root cap and epidermis mostly of a common ontogenetical origin. Plants woody or herbaceous, frequently secondarily arborescent. Epicuticular wax ultrastructure mostly of Aristolochia-type, but in Winteraceae and Canellaceae they are of Berberis-type. Plastids of the sieve elements of S-type or less often of P-type. Flowers mostly 5- or (less frequently) 4-merous and only in some mainly archaic groups 3-merous. Floral nectaries of various types but never septal or nectaries absent. Pollen grains typically triaperturate or of triap-erturatederived type, except in some archaic families, where they are distally uniaperturate or rarely biaperturate. The class Magnoliopsida includes 8 subclasses, 125 orders, c. 440 families, almost 10,500 genera, and no less than 195,000 species.