Plant Common Name
Buttery slices of ripe avocado on sandwiches, thick, rich guacamole, milkshakes and salads are just a few of the uses for the versatile fruit of Persea americana. Native to the area from the Rio Grande south through Peru, this tree has been cultivated for centuries. It is now grown worldwide in subtropical and tropical regions as a commercial crop, in home landscapes and orchards.
Extremely variable trees, avocados may be tall and erect to moderately-sized and spreading. The leaves are large, alternate on the stem, glossy, dark green on the upper surface and pale to whitish underneath. Leaf shape is also dependent on variety from elliptical or lance-shaped to oval. Semi-evergreen, the leaves may fall continuously throughout the year or during the dry season.
Many small, fuzzy flowers without petals are produced on un-branched spikes near the ends of the branches from mid-winter through late spring; the exact bloom date is dependant on variety.
There are two flowering classes of avocado, Class A and Class B. These are distinguished by the time of day that the flowers open and are designed to keep the flowers from self-pollinating.
Class A: New flowers open in the morning. The flowers do not shed sperm-carrying pollen, but the female organ, called the pistil, is receptive to outside pollen and gets fertilized. The flowers close at midday and stay closed until the afternoon of the following day. Then the blooms reopen, but this time the flowers shed pollen, and fertilized pistil is no longer receptive.
Class B: New flowers open in the afternoon. The flowers do not shed sperm-carrying pollen, but the female organ, called the pistil, is receptive to outside pollen and gets fertilized. The flowers close at dusk and stay closed until the morning of the following day. Then the blooms reopen, but this time the flowers shed pollen, and the fertilized pistil is no longer receptive. For good pollination, growers should plant both Class A and B type flowering trees in close proximity.
Fruit, high in unsaturated oil content follow the flowers and ripen from six to eighteen months after flowering. The shape of the fruit is oval to egg-shaped to pear-shaped and small to very large. The skin maybe smooth or rough and variously tinted, bright green, yellow-green to red-blushed or purple. Inside most fruits is a large, hard, papery-skinned seed. Avocados may be grown from seed, but the best trees are grafted for earlier fruiting and to preserve desired variety characteristics.
Avocados are classified into three types based on the area of origin of the trees. The Mexican varieties are native to the mountains of Mexico south to Chile. The Guatemalan varieties are native to highlands of Central America, Ecuador and Mexico. The West Indian varieties are native to lowlands of Central and South America and where introduced to West Indies in the late 1600’s. There are many hybrids among the variety types which exhibit characteristics of both.
These versatile trees are tolerant on many types of soil, but most require well-drained conditions. Full sun is best for good growth and fruit production. Drought tolerant once established, avocado fruiting is best when watered regularly during production. They are large trees and require plenty of space for growth. The wood is somewhat brittle and high winds can break branches and dry out the flowers thereby reducing fruiting. Avocados are generally freeze sensitive, though some varieties will takes temperatures a few degrees below freezing for a few hours while others will show damage from light frost.
Avocado trees are beautiful as ornamentals; use them as specimens or shade. They are easy trees to grow and productive in home orchards.