Avocados (Persea Americana) carry the catchy common name of alligator pears thanks to the dark lizard green, warty skins of the edible fruits. Native to tropical parts of Central America, avocado trees typically grow 35 to 60 feet tall and 50 to 80 feet wide. A mature tree looks like a large-leaved live oak. The avocado tree's foliage generally remains evergreen, although excessively dry winters or temperatures close to freezing causes partial leaf drop. Grow avocado trees outdoors year-round in U.S. Department of Agriculture plant hardiness zones 9 and warmer.
Look at the foliage to quickly determine if the tree's leaves somewhat resemble those of an avocado. A true avocado produces leaves that are large, round or elliptic in shape, with a smooth edge. There are no lobes or leaflets.
Examine the leaf blade. An avocado leaf measures between 6 and 12 inches long and 3 to 6 inches wide. Glossy light to medium green in color with lighter, faintly fuzzy undersides, each leaf displays prominent veins. The upper leaf side reveals an obvious midrib with many branches, all a slightly lighter green-yellow color than the leaf tissue.
Look at the tree's branch tips, if possible. Newly emerging leaves possess a pinkish russet coloration as they enlarge, eventually becoming green. In addition, look at the ground under the tree. Avocado tree leaves are slow to decompose and often accumulate in thick mounds on the ground.
Crush a leaf and smell it. Huge variations in odor exist among avocado trees. Kirsten Albrecht Llamas, author of "Tropical Flowering Trees," notes that no odor wafts from crushed avocado leaves. However, Margaret Barwick, author of "Tropical and Subtropical Trees," attests that trees with a Mexican genetic lineage tend to release an anise scent from crushed leaves. This is in contrast to the fragrance-free leaves of West Indian and Guatemalan types of avocado trees.