BRIEFER ARTICLES 



ERRORS IN DOUBLE NOMENCLATURE 



In naming plants having so few well marked individual features as 

 the micro-fungi, it is natural that the appellations should often be taken 

 from the charactef of the substratum. Among the Uredinales names 

 are frequently derived from the hosts on which they are found; thus 

 Aecidium AesctiU is so named because it grows or was believed to grow 

 on Aesctdus. Many collections of rusts include simply the leaves of 

 the host, or only fragments of leaves or of other parts. Mycologists 

 generally depend upon the collector or some phanerogamic specialist 

 to supply the host determination. The critical taxonomist, however, 

 must be on the alert to. detect anything that might possibly invalidate 

 the name applied to the host, as well as to make sure of the correctness of 

 the name given to the parasite. Thus it comes about that the taxonomic 

 uredinologist must deal in double nomenclature, that pertaining both to 

 the host and to the fungus. To misapprehend the identity of either the 

 host or of its unbidden guest may entail deplorable consequences. 



The object of this note is to point out a curious error of this sort, 

 which went through the hands of more than half a dozen able tax- 

 onomists undetected before passing into print. In the account of the 

 rusts collected by Dr. and Mrs. J. N. Rose in the Andes, given by the 

 writer in the Botanical Gazette for May 1918 (p. 470), 2 new species 

 are proposed, both on Solanaceous hosts. One is Piiccinia Nicotianae 

 on a species of Nicotiana, and the other following is P. Acnisti on a 

 species of Acnistus. If the descriptions of these 2 species be compared, 

 they will be found to be remarkably similar. In fact, the only important 

 difference? are that the first gives measurements for more globoid 

 urediniospores, and makes the wall of the teliospore slightly thicker above 

 and verrucose instead of smooth, as compared with the second. These 

 descriptions were drawn up independently by different workers, and 

 were not closely compared until taken in hand by a third investigator 

 after they were published, who undertook to fit them into a general 

 key. Upon reexamining the specimens these differences vanish. The 

 variation in length of urediniospores is greater than the first description 

 states, the teliospores are not really thicker above, and their surface 

 is obscurely verrucose, although sometimes seemingly smooth. 



147] [Botanical Gazette, vol. 68 



