The fruits called plums (or prunes) belong to the Prunus species (Prunus domestica or Prunus x domestica) that has several varieties including some hybrids. Most of the plums sold in the market belong to this species, or its subspecies, or its hybrids, though there are other plums that do not belong to this species.
Prunus domestica is believed to be of the hybrid parentage of Prunus spinosa and Prunus cerasifera var. divaricata, and belong to the family Rosaceae. It also has several subspecies and hybrids with commonly known names such as damsons, Damask plums, greengages, zibarte, mirabelle, etc.
Because plants of this species and its subspecies can be hybridized or crossed easily, there are many similar looking plums with different types of tartness and sweetness. The fruits can be of various sizes, though the common varieties may be having a diameter of about 8 cm (about 3 inches). The fruits may be of various colors such as light green, bluish purple, yellow, orange, or red.
Prunus domestica can grow to the size of a small tree or a large shrub, often with a thorny appearance. The flowers are white and mostly bloom in early spring.
Plums are nutrient-rich and provide adequate quantities of sugars, dietary fiber, protein, Vitamin A, Vitamin C, phosphorus, potassium, other vitamins and trace minerals, etc.