NORTH AMERICAN SPECIES OF THE GENUS AMYGDALUS.^ 



William Franklin Wight, 

 Bureau of Plant Industry, Washington, D. C. 



THE SPECIES which form the subject of the present paper have been 

 referred to both Prunus afid Amygdalus by various authors who have 

 had occasion to consider them. They are, however, so distinct from 

 all other species of Prunus in America as at once to suggest the propriety 

 of constituting a new genus. This in fact was done by Torrey^ for one 

 species of the group, he having published the genus Emplectocladus in 1854. 

 Notes on a few specimens in the herbarium of the Museum d'Histoire Nat- 

 urelle at Paris indicate that Spach who studied the Amygdalaceae as thor- 

 oughly as any one of his time, also had under consideration the recognition 

 of the genus Emplectocladus. A study of the material preserved in some 

 of the European herbaria, however, shows conclusively that they cannot be 

 separated from certain Asiatic species which are referred to Amygdalus by 

 authors, who recognize the latter as a genus distinct from Prunus. In fact, 

 the' Asiatic species apparently show a gradual but complete transition from 

 this North American group to the species of Amygdalus common in cultiva- 

 tion. Again, while the groups Padus and Laurocerasus appear to be sep- • 

 arable from true Prunus by well-defined characters, it must be admitted that 

 when all the species are considered, the groups Prunus and Amygdalus show 

 no such well-marked diagnostic characters, even though their extremes are 

 different enough. Nevertheless^ unless these two groups are recognized as 

 separate genera, to speak or write of a given species as belonging to Prunus 

 conveys little conception of its true character, or to what economic species it 

 may be most closely related. Since nomenclature cannot well be made to 

 express accurately the relationship of species, but is, first of all, a matter of 

 convenience, the present author would retain the name Amygdalus for the 

 peach and almond-like species. And while this group may not be readily 



1 In the preparation of this paper the author has consulted the material in the 

 following herbaria: the Gray Herbarium, Arnold Arboretum, New York Botanical 

 Garden, United States National Herbarium, Missouri Botanical Garden, Field 

 Museum, University of California, Leland Stanford Jr. University, Kew Gardens, 

 and the Museum d'Histoire Naturelle of Paris. The curators of these collections 

 have kindly made available the material in their charge and for this the writer 

 wishes to express his appreciation. 



2 Torrey, John, Smithsonian Contributions VI. (Plantae Fremontianae 10. t. 5. 

 1854.) 



