 It can easily be confused with the related "Prunus americana", differing most obviously in the leaf margins having blunt, gland-tipped teeth, rather than the sharp, glandless teeth of "P. americana" leaves.A fungus in the genus "Taphrina" often attacks the plums; the young ovaries swell, often much larger than full grown plums, become hollow and often persist on the tree in winter.Known as "plum pockets", they appear pale green, leathery to the touch, and hollow with the exception of a few fibrous bands.