The surest way to identify that a plant is an evergreen shrub is to stand around and make sure its leaves remain on during the winter. However, even if you have this type of patience, you still will not know exactly what kind of evergreen shrub a certain species is. This is where a field guide to shrubs and your ability to discern the many features of a plant become important. Pay attention to the many facets of the leaves, the size of the shrub and its other features and you can tell one shrub apart from another.
Look at the height of the shrub. Taking an evergreen shrub called mountain laurel as your example, you would look for a shrub that is normally between 4 and 12 feet high. Remember that in certain cases, mountain laurel included, a shrub may also fall under the category of a small tree if it grows tall enough, as many can.
Check out where you find a shrub growing. Some shrubs have a tendency to grow in specific soils or in particular settings. Mountain laurel is a shrub that often thrives on rocky slopes and hilltops.
Measure the leaves of the shrub for width and length. Once you have this information you can check it against that in your shrub field guide. Going back once more to mountain laurel, you would see that the average leaf is about 2.5 to 4 inches long and as wide as 1.5 inches.
Observe the shape of the leaves. Determine if they are lobed, elliptical, oval or any of the other shapes that evergreen shrub leaves may be. Mountain laurel has what the National Audubon Society Field Guide to trees calls "lance-shaped" leaves. Descriptions like this make identifying the shrub much less problematic.
Look at other features of the leaves that may aid in recognizing the shrub in your field guide. Ask yourself if the leaf is thick, glossy, rubbery or smooth and if it has any special colors. The mountain laurel leaf will have a dull green upper surface but be more of a yellowish-green color beneath. Facts like this can narrow down your choices.
Study the flowers, if there are any, on an evergreen shrub. The size, shape, fragrance, color and positioning of the blossoms are important data that you can use. Mountain laurel has such attractive flowers that they are Connecticut's state flower. They have a saucer shape, five lobes and are pinkish or white.