6 JOURNAL OF THE ARNOLD ARBORETUM [vol. vi 



designed merely for convenient reference and to facilitate the identi- 

 fication of material. The very unusual size of this genus in number of 

 species, the bulk of material in our herbarium and the large accessions 

 constantly accumulating, as well as specimens and collections frequently 

 being received for identification from various parts of the country 

 became so burdensome, even with the ample library and collection of 

 types available here, that it was thought worth while to bring together 

 in as compact a form as possible a synopsis of the information scrttered 

 through many publications and indices. It was hoped also that it might 

 at some future time serve as the basis for a fuller study and more complete 

 key to the genus. It is published with some reluctance at this time 

 in the hope that it may prove of wider use and convenience to students 

 of American Crataegus, especially to those who do not have access to 

 much of the original literature or to the collections of the larger herbaria. 



It is intended in the index to give a list as complete as possible of 

 the specific and varietal names that have been applied to North American 

 Crataegi. Possibly some names have escaped the writer's attention 

 that should have been included, and many of those listed are given only 

 for reference. No attempt is made to give a complete synonymy under 

 valid names nor of combinations under other generic names. Specific 

 names that have been variously interpreted by different botanists are 

 included but once, exception being made in a few cases where it seems 

 evident that duplication occurred through coincidence and that the 

 authors were referring to different plants. Several instances of this 

 sort will be noted, some of which are corrected in a paper by Professor 

 C. S. Sargent appearing in this issue. 



As this paper is not intended as a critical study in the sense of a revision 

 of the genus, I have carefully refrained from making new combinations 

 and so far as possible from going into the question of the validity of 

 names that have been published. However, for the sake of clearness 

 it was found necessary to indicate that certain names are recognized 

 synonyms of others and where these have been used both as of specific 

 and varietal rank to designate the preferred form. In such cases the 

 practice prevailing at present in the Herbarium of the Arnold Arboretum 

 has naturally been followed and names regarded as synonyms are printed 

 in italics. A few obvious orthographical errors in previous publication of 

 names have been corrected and for the sake of uniformity the practice of 

 doubling the final i after consonants except after the ending "er," as recom- 

 mended in the International Rules of Nomenclature, has been adopted 

 for all names recognized as valid. 



The question of synonymy and priority of names in this genus is much 

 complicated by the fact that many North American species were first 

 named from specimens cultivated in European gardens. These names 

 were often without adequate descriptions or figures or with none at all, 

 and in almost all cases without any definite records as to the part of the 



