Plum has many species, and taxonomist differ on the count.
Depending on taxonomist, between 19 to 40 species of plum exist.
From this diversity only two species, the hexaploid European plum
(Prunus domestica) and the diploid Japanese plum (Prunus salicina
and hybrids), are of worldwide commercial significance. The origin
of these commercially important species is uncertain but may have
involved P. cerasifera and possibly P. spinosa as ancestors. Other
species of plum variously originated in Europe, Asia and America