HYBRID PLUMS 



By F. A, Waugfa, Dcpt. of Horticulture, Massachusetts Agricultural G>IIege, 



Amherst, Mass. 



A large number of hybrid plums has appeared on the scene in America 

 during the last few years. They have aroused considerable interest, and 

 many of them have been rather extensively planted. There is, therefore, a 

 good deal of information extant regarding their behavior and a healthy 

 demand for further information. Such matters as have come within the 

 scope of my own observation and experiment have been presented in various 

 articles — principally in the publications of the Vermont experiment station. 



In the papers referred to I have described a considerable number of 

 varieties, old and new, and have given the historical data regarding their 

 origin. In many cases the question of parentage and affiliation has been 

 discussed. It has been shown, also, that various species participate much 

 more frequently in garden hybridization than do others ; and various sug- 

 gestions have been made in connection with these observations for the further 

 breeding of plums. 



One observation which has been repeatedly made, and which I wish to 

 make the principal point of this discussion, relates to one of the fundamental 

 laws of hybridity. It" has usually been laid down as true that offspring of 

 the first generation from two specific parents will greatly resemble one 

 another. There is likely to be a wide range of variation in the second gen- 

 eration, but the first crosses are said to be usually very uniform. In plants 

 propagated by buds this uniformity will, of course, be preserved by grafting 

 or similar means, and it becomes more interesting on that account. 



The general law quoted above seems to be verified among the hybrids 

 already produced in the genus Prunus. While the uniformity is not always 

 so striking as would justify the law aside from experience in other genera, 

 still it is sufficiently obvious to be worthy of note. The offspring from 

 any given pair of specific parents seem to be quite as uniform as any of the 

 other common groups among the plums. It is a well known fact, of course, 

 among pomologists, and even among botanists, that all or nearly all our 

 species of Prunus are very variable. Anything like a reasonable degree of 

 uniformit}', therefore, in a group of hybrid offspring should be accepted as 

 worthy of remark. 



The three species which have been most frequently used in hybridization 

 experiments in this country, and which have also bred most readily with each 

 other in the field, are Prunus horlulana, P. triflora and P. simonii. The 

 most common cross is the one between the two first named. These hybrids 

 have appeared naturally and artificially literally by thousands ; and a large 

 number of them have been named, described, propagated and distributed. 



