The first great division among the vascular plants separates the spore-producing plants from those that reproduce through the formation of seeds. In this class distinction, the much smaller group of seedless vascular plants can be distinguished by a small-sized, herbaceous stalk with primitive leaves and, in most cases, a spore case that forms on the underside of its leaves. These plants also have rhizomes instead of a true root system.
The next separation occurs between the conifers and the flowering plants. The conifers are easy to tell apart because they formed cones, have needle-like leaves and almost always have a woody stem or trunk. That leaves the angiosperms, which are easily identified by the formation of a flower.
A close look at the leaf will be the key deciding factor in the next step, which separates the monocots from the dicots. Monocots have parallel-veined leaves, while the dicots have a leaf with intersecting lines or veins. The monocots are predominantly herbaceous, while the dicots come in a form of a herb, shrub or a tree.
These flowering plants are a large diverse group that includes many shrubs and trees and well as wildflowers. These plants need to be identified to family, which sometimes can be done with just a quick glance (i.e. an oak or a maple) and then further separated and identified to species with the aid of a plant key or book.
These plants are considered to be the most highly evolved of all the plants. Except for a few woody palms, this group is mostly herbaceous containing some very large and common families of plants that include the grasses, the composites (daisies, sunflowers, asters), the orchids and the lilies.