Classification of Flowering Plants

The Magnoliophyta is such a large group with so many families, genera, and species that it is rare for an individual taxonomist to attempt to study and classify the entire group. The most recent monograph of the entire division is An Integrated System of Classification of Flowering Plants (1981, Columbia University Press) by Dr. Arthur Cronquist of the New York Botanical Garden. Dr. Cronquist's classification is followed here.

Soon after their origin, flowering plants began to follow two distinct lines of evolution, and at present there are two classes: (1) class Liliopsida, the monocots, and (2) class   Magnoliopsida, the dicots (Table). No single character always distinguishes a monocot from a dicot, and some species would fool most botanists. In general, monocots, as their          name implies, have only one cotyledon on each embryo, and other typical characters are the following: Their leaves usually have parallel veins because the leaves are elongate and strap-shaped (grasses, lilies, and irises); vascular bundles are distributed throughout the stem, not restricted in one ring; monocots never have ordinary secondary growth and wood. Flowers of monocots have their parts arranged in groups or multiples of three: three sepals, three petals, three stamens, and three carpels . Dicots are much more diverse and include a greater number of families, genera, and species. Dicots have two cotyledons usually and reticulate venation in the leaves; vascular bundles occur in only one ring in the stem. Dicots can be woody, herbaceous, or succulent or have any of many highly modified forms. Flower parts occur in sets of five most often , sometimes in sets of four, but only rarely in sets of three.