Like most perennial fruits, apples are ordinarily propagated asexually by grafting. Seedling apples are different from their parents, sometimes radically. Most new apple cultivars originate as seedlings, which either arise by chance or are bred by deliberately crossing cultivars with promising characteristics. The words "seedling", "pippin", and "kernel" in the name of an apple cultivar suggest that it originated as a seedling. Apples can also form bud sports (mutations on a single branch).
Some bud sports turn out to be improved strains of the parent cultivar. Some differ sufficiently from the parent tree to be considered new cultivars. Some breeders have crossed ordinary apples with crabapples or unusually hardy apples in order to produce hardier cultivars. For example, the Excelsior Experiment Station of the University of Minnesota has, since the 1930s, introduced a steady progression of important hardy apples that are widely grown, both commercially and by backyard orchardists, throughout Minnesota and Wisconsin. Its most important introductions have included 'Haralson' (which is the most widely cultivated apple in Minnesota), 'Wealthy', 'Honeygold', and 'Honeycrisp'. The sweetness and texture of 'Honeycrisp' have been so popular with consumers that Minnesota orchards have been cutting down their established, productive trees to make room for it, a heretofore unheard of practice. Today, apples are of course grown throughout the temperate, warm temperate, and to small degree, subtropical world.
Apples are an unique fruit in that they have a variety of flavors, degrees of sugar and acid, different flesh textures, and differing juiciness. The number of varieties is legion, but only a very few are produced commercially. Some of the less commercially acceptable varieties are smaller, less juicy, more acid, have very 'hard' dense flesh, and probably have a great deal more fiber than more 'melting' fine fleshed commercial cultivars. They may perhaps be more like the wild apples our ancestors ate. These connoisseur varieties can be found sold 'at the gate'. Unfortunately, there is a trend to produce and market fruit which are too large, especially for children. And some fruit is picked not fully tree ripened, which can be disappointing. New varieties may alleviate these problems. Apples vary from a 'fairly good' to a 'very good' source of vitamin C, as there are significant between the varieties. 'Crab apples', possibly Malus sylvestris, are listed as having very little vitamin C content (compared weight for weight to modern apples). Given the great number of selections of ornamental crab apples, this measurement may not necessarily apply to wild crab apples, or all species of wild crab apples, at least. Apples are a good source of the B vitamin 'biotin'. Apples are also a good source of a variety of minerals-magnesium, iron, chromium, and manganese. Apples ( as distinct from the expressed juice) are a good source of soluble fiber, which has been shown to slow the release of sugars in the blood and also slightly drop blood cholesterol levels.