Let's Get It On

Most apples are self-incompatible and must be cross-Bumble bee filled with pollenpollinated to develop fruit.  Many varieties of apples and crabapples have viable and compatible pollen for reproduction.  This pollen is carried from one flower to another flower on a different tree by pollinators.  The main pollinators of Malus domestica are bees.  This can include many types of bees like honey bees, rusty-patched bumble bees, carpenter bees, and orchard mason bees.  These bees are attracted to nectar produced in the flower.
 Angiosperm Life Cycle
Like all plants, Malus domestica has a life cycle with an alternation of generations.  This means that the organism grows and alternates between a haploid stage (n) and a diploid state (2n).  The image shows a general sexual life cycle of all angiosperms.  The left side of the image shows a female gametophyte developing an embryo sac.  The right side of the image shows a male gametophyte developing a pollen grain.  At the bottom of the image the pollen fertilizes the embryo sac to form a zygote, which is the seed.