14 THE PLUMS OF NEW YORK. 



in this species, among others, plums which we now place in Prunus cerasi- 

 fera, the Cherry plums, and Prunus insititia, the Damsons and Bullaces. 

 Nearly all subsequent botanists who have not made two or more species 

 of it have recognized from two to several sub-divisions of Prunus domestica. 

 It is possible that what are called the Domestica plums should be distrib- 

 uted among several botanical divisions. But it is difficult to find any 

 differential character sufficiently constant to distinguish more than one 

 species for the several hundred varieties of these plums now under culti- 

 vation. Nor are there any cleavage lines sufficiently distinct to indicate 

 that the edible varieties of the one species should be sub -grouped. 



In coming to these conclusions the writer has studied about three 

 hundred varieties of Domestica plums growing on the grounds of this 

 Station and about half as many more growing in other parts of the country, 

 the whole number representing all of the various species and sub-species 

 which other workers have made. The differences which have been most 

 used to classify the varieties of Domestica in several botanic divisions have 

 to do chiefly with the fruit, as size, shape, color and flavor, characters so 

 modified by cultivation and selection that they are artificial and transitory 

 and of little value in botanical classification. Moreover, the botanical 

 groups which have been founded on these characters are much more indis- 

 tinct than ordinarily in botany because of the merging at many points 

 of one group into another. This indistinctness is greatly increasing year 

 by year through the intercrossing of varieties. When the characters of 

 no value to man, and, therefore, little modified by cultivation, are con- 

 sidered, it is scarcely possible logically to place Domestica plums in more 

 than one species or to further sub-divide the one species. 



The botanists who have divided the Domestica plums into either 

 greater or lesser botanical groups do not define their divisions with suffi- 

 cient accuracy to make them clearly recognizable. Neither do they give 

 the habitats of the wild progenitors with sufficient certainty to carry con- 

 viction that the groups were brought under cultivation from separate 

 ancestors. Also, the several botanists who hold to the multiple species 

 theory for the Domestica plums do not agree as to the limits of the different 

 groups and give to them very different specific or variety names, showing 

 that they have widely different ideas as a basis for their classification. 



A second theory is that Prunus domestica is derived from Prunus 

 spinosa and that Prunus insititia is an intermediate between the two. 1 



'Bailey, L. H. Cyc. Am. Hort. M47- 1901; Hudson Fl. Anglic. 212. 1778. 



