Prunus spinosa the more shrubby habit with stiffer, wider-angled branches of "P. spinosa"; in summer by the relatively narrower leaves of "P. spinosa", more than twice as long as broad; and in autumn by the colour of the fruit skin purplish black in "P. spinosa" and yellow or red in "P. cerasifera". "Prunus spinosa" has a tetraploid (2"n"=4"x"=32) set of chromosomes. The specific name "" is a Latin term indicating the pointed and thornlike spur shoots characteristic of this species. The common name "" is due to the thorny nature of the shrub, and its very dark bark. The word commonly used
Prunus simonii is particularly aromatic, much more so than "Prunus salicina", with a comparatively high level of hexyl acetate, which gives apples their aroma. Plant breeder Luther Burbank devoted a lot of work to hybridizing this species with the Japanese plum ("Prunus salicina") and developed a number of cultivars from the hybrid. Of these, the cultivar 'Climax' was particularly notable for its importance to the fruit shipping industry of California. Other influential plum cultivars that Burbank developed with "P. simonii" ancestry include 'Maynard', 'Chalco', 'Santa Rosa', and 'Formosa'. Those two species and the European species "Prunus cerasifera" have contributed the majority of