Crabapple
This is a name given to very small and sour apples, wild or cultivated, from any number of species in the genus Malus.
These trees are grown all over the world and have a history of local use from very early times.
Generally, crabapples are edible and nutritious; but most of them are extremely sour and astringent, requiring the addition of much sweetener to make palatable jams and jellies.