The Pecan (Carya illinoinensis, commonly misspelled illinoensis) is a species of hickory, native to south-central North America, in the United States from southern Iowa, Illinois and Indiana east to western Kentucky and western Tennessee, south through Oklahoma, Arkansas, to Texas, Mississippi, and Louisiana; and in Mexico from Coahuila south to Jalisco and Veracruz.
The pecan tree is a large deciduous tree, growing to 20–40 m (65-130 ft) in height, rarely to 44 m (145 ft); taller trees to 50–55 m (165-180 ft) have been claimed but not verified. It typically has a spread of 12-23 m (40-75 ft) with a trunk up to 2 m (10 ft) diameter. A 10-year-old sapling will stand about 5 m (16 ft) tall. The leaves are alternate, 40–70 cm long, and pinnate with 9–17 leaflets, each leaflet 2–1 cm long and 2–7 cm broad. The flowers are wind-pollinated, and monoecious, with staminate and pistillate catkins on the same tree; the male catkins are pendulous, up to 18 cm long; the female catkins are small, with three to six flowers clustered together. The fruit is an oval to oblong nut, 2.6–6 cm long and 1.5–3 cm broad, dark brown with a rough husk 3–4 mm thick, which splits off in four sections at maturity to release the thin-shelled nut. Pecans, like the fruit of all other members of the hickory genus, are not true nuts but technically a drupe (fruit with a single stone or pit). The husks are produced from the exocarp tissue of the flower while the part known as the nut develops from the endocarp.
Pecans first became known to Europeans in the 16th century; the Spanish explorer Cabeza de Vaca saw and wrote first about this plant. The Spaniards brought the pecan into Europe, Asia, and Africa beginning in the 16th century.
The nuts of the Pecan are edible, with a rich, buttery flavor. They can be eaten fresh or used in cooking, particularly in sweet desserts but also in some savory dishes. One of the most common desserts with the pecan as a central ingredient is the pecan pie, a traditional southern U.S. recipe. Pecans are also a major ingredient in praline candy, most often associated with New Orleans.
Pecans were one of the most recently domesticated major crops. Although wild pecans were well-known among the colonial Americans as a delicacy, the commercial growing of pecans in the United States did not begin until the 1880s. Today, the U.S. produces between 80% and 95% of the world's pecans, with an annual crop of 150–200 thousand tons. The nut harvest for growers is typically around mid-October. Historically, the leading Pecan-producing state in the U.S. has been Georgia, followed by Texas, New Mexico and Oklahoma; they are also grown in Arizona and Hawaii. Outside the United States, pecans are grown in Australia, Brazil, China, Israel, Mexico, Peru and South Africa. They can be grown approximately from USDA hardiness zones 5 to 9, provided summers are also hot and humid.
Pecan trees may live and bear edible nuts for more than three hundred years. They are mostly self-incompatible, because most cultivars, being clones derived from wild trees, show incomplete dichogamy. Generally, two or more trees of different cultivars must be present to pollenize each other.
Pecans are a good source of protein and unsaturated fats. A diet rich in nuts can lower the risk of gallstones in women. The antioxidants and plant sterols found in pecans reduce high cholesterol by reducing the "bad" LDL cholesterol levels.
Clinical research published in the Journal of Nutrition (September 2001) found that eating about a handful of pecans each day may help lower cholesterol levels similar to what is often seen with cholesterol-lowering medications. Research conducted at the University of Georgia has also confirmed that pecans contain plant sterols, which are known for their cholesterol-lowering ability.
The U.S. Food and Drug Administration (FDA) has acknowledged this and related research and approved the following qualified health claim: "Scientific evidence suggests, but does not prove, that eating 1.5 ounces per day of most nuts, such as pecans, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. "This nut is an important source of ellagic acid. Pecan nuts are a good low fat source of vitamin E and also have anti-cancer effects. They can also, if eaten correctly, lead to lower cholesterol levels.