82 Plums and Plum Culture 



With plants occurring wild, the distribution of a 

 strange form is an important evidence of hybridity, as 

 in the case of Primus hortulana; and for a study of hy- 

 bridity in general, authentic pedigrees are indispensa- 

 ble; but for all practical, and for most scientific pur- 

 poses, intermediateness of character is the only practi- 

 cable and 'the most reliable test of hybridity. 



The greatest caution, however, must be exercised 

 in following out this rule. It will not do to jump at 

 conclusions in such an intricate matter. No one can 

 determine at the first glance whether the characters 

 of a new variety are drawn from several definable 

 sources. It is often difficult to decide what the rela- 

 tionships of a given variety are, even after long study 

 of all the characters of plant, foliage, blossom and 

 fruit. It is a very serious problem to classify some 

 varieties which belong to only one species! Before the 

 pomologist refers a new plum to two species, he must 

 give the evidence his most searching scrutiny. 



In the present work the hybrid plums are put into 

 a group by themselves. It will be increasingly diffi- 

 cult and unsatisfactory, as time goes on, to maintain 

 this group and to mark its boundaries. There is noth- 

 ing homogeneous about a group labeled "hybrid 

 plums." What does a hybrid plum look like? Why, 

 like Primus simonii, or perhaps like a Chicasaw, or 

 maybe like an Americana. It is necessary, therefore, 

 if we are to tell anything about the varieties which we 

 classify as hybrids, to add something to the classifica- 

 tion. When we say a plum belongs to the Wayland 

 group, any plum expert has a pretty good idea of what 

 the variety is like. But when we say a variety is a 

 hybrid, he Knows nothing about it. 



The natural way to classify a hybrid is to name 

 the parents from which it has sprung. But such a 

 classification is misleading unless the hybrid variety 



