Apples are among the most popular fruits in the world. They come in a wide range of shapes, sizes, flavors and textures. Apple trees can grow quite large, and yet, their life cycle begins with little seeds found within the apple fruit itself.
There are between five and 10 seeds within each apple on average. Each seed contains a tiny portion, referred to as the germ. This part of the seed holds the genetic material from which the tree will grow. The seed also contains food stored as starches. A hard seed coat encases the seed, protecting it.
Once freed from the fruit, the apple seed will require a certain amount of time at cold temperatures before it will germinate. This process is referred to as breaking dormancy and usually takes three to four months at sub-freezing temperatures. Once winter has passed and spring has come with warmer temperatures, if conditions are right, the seed will germinate.
As the seed grows, it will put forth a root, which will grow downward into the soil. It will form root hairs that gather moisture and nutrients for the plant to grow. The stem will sprout, forming small leaves, which will also help to nourish the tiny plant. The young apple tree will grow one to three feet in the first season, forming a single leader trunk and several branches with leaves.
As the tree continues to grow, it struck will become heavier and will sprout and support multiple branches. Leaves on each branch will continue to grow. The apple tree is deciduous and will drop its leaves in winter during a period of dormancy. In the spring, it will sprout leaves again and continue to grow during the warm seasons, eventually reaching a height of up to 25 feet and spreading to an equal distance. Dwarf varieties will usually grow no higher than 15 feet.
In the spring, mature apple trees will flower profusely. The flowers formed in dense clusters along the branches prior to leaves sprouting. Each flower has five petals and is approximately 1/2 to 1 inch in diameter. A cluster of male anthers within each flower produces pollen. This pollen is attractive to insects, particularly honey bees. Because each apple variety requires cross pollination with a different variety of apple, commercial apple growers often employee beekeepers to provide pollination services by placing beehives in their orchards. The bees will visit each flower and, in the process, will transfer the pollen from the anther of one apple variety to the female portion, called the stigma, of another apple variety. The pollen will then release sperm that will travel down through the stigma into the ovary where fertilization will occur and seeds will begin to form.
Once fertilization is complete, the petals of the flower will fall away. The base of the flower will then begin to grow, eventually forming a fruiting body, known commonly as an apple. As it grows the seeds will mature within it. This process usually takes from spring to fall for the apple to reach full maturity. At this time, the apple to be harvested. If left unharvested, the apple will eventually fall to the ground. The fruit may rot or may be eaten by an animal that will carry the seeds to a new location in its gut. The animal will pass the seeds, which may then germinate to start the life cycle of the apple tree over again.
Apple trees do not produce true from seed. This means that the seeds produced by apple tree will not necessarily grow into trees that will produce fruit identical to its parent. This is because apple trees are cross-pollinated. In commercial production, apple trees are often propagated by growing new trees from cuttings and grafting. This process ensures that the genetics of the new plant are identical to that of the old plant. New plants will then produce fruit that is identical to the parent.