Although it is actually the surface area of the leaves that matters rather than the number, it has been estimated that it takes the photosynthetic energy from 50 apple leaves to produce one apple.

Apples float because they are 25 percent air and bruise easily because they are 25 percent water.

The apple tree originated in Central Asia, where its wild ancestor, Malus sieversii, is still found today.

Over 7,500 cultivars of the culinary or eating apple (Malus pumila) are known. The vast majority, however, are not suitable for mass production.

Apples act like natural stain removers by increasing saliva production, which serves as the mouth's self-cleaning agent. They also kill some kinds of bacteria that cause bad breath, and their crunch factor works to scrub teeth clean. Apples are also known to improve eyesight. Flavonoid compounds and antioxidant phytonutrients reduce the effect of free radicals on eyes and prevent many eye diseases.

Apples generally ripen between August and September. They are picked when they are slightly unripe, treated with a chemical called 1-methylcyclopropene, waxed, boxed, stacked on pallets, and kept in cold storage warehouses for an average of 9-12 months.

Due to their relatively high proportion of fructose, apples have a lower glycemic index compared to other sweet fruits, which means they have less impact on blood glucose levels and insulin release. Consequently, apples are an allowable snack for diabetics if eaten in moderate amounts and portions.

The average healthy and well-cared-for apple tree can live for 50 to 80 years. However, there are striking exceptions to this rule. Some apple trees have been reported to live for more than a century.

According to the U.S. Apple Association, Red Delicious has been the nation's top-selling apple for at least five decades.

Crabapples preceded European colonists to America, but the fruit was not very edible. Other varieties were brought by settlers in the 1600s.