PLA^T NOMEXCLiTURE 115 



nearly aiitoiiiatic system. Every name wliieh is an exception to rule 

 is a clog in the nomenclature-machine, and is liable to bring about 

 surprising cross-complications. Consequently for small genera, where 

 any change involves the learning of only a few new names, it seems 

 to me that we should agree to discard uniformly all antedated names ; 

 but for large genera, practical convenience, including continued quick 

 accessibility to literature for students of many branches of botany, 

 requires, I think, the retention of some widely-used names. 



A suggested plan of harmony on this vexed matter is then to 

 nmintain a list of nomina conservanda, placing thereon such ante- 

 dated current names as have been applied to genera credited with 

 at least a hundred species — possibly the limit should be fifty. In 

 either case such a list would be small, involving few exceptions to 

 rule, and would be found nevertheless to include the great majority 

 of those species whereon the codes at present disagree. 



To test the truth of this contention, and also to prove to our- 

 selves how much less than has been supposed is the present divergence 

 in actual practice between the two codes, let us examine a sample 

 portion of the 'list of nomina conservanda authorized at Vienna in 

 1907. I assume that the list of New England nomina conservanda^ 

 published in Bliodora, ix. 53, 1907, is a fair specimen of the whole. 

 Let us examine these names and see what proportion, forming a 

 reserved list only for names given to genera of fifty or a hundred 

 species, need be maintained on a restricted list of names to be con- 

 served. To check the size of each genus we will assign it the 

 number of species given it in Dalla Torre et Harms, Genera Siphono- 

 gamarum ; and, as indicating the action of the American Code, we 

 will compare its nomenclature with that of Dr. N. L. Britton in 

 Britton & Brown, Illustrated Flora, ed. 2, 1918. 



Excluding Eropliila DC. (not in Genera Sij)honogamarum as a 

 distinct genus), there are listed 61 names of genera occurring either 

 as native or as introduced in New England. Of these, 1(S should be 

 excluded, inasmuch as the American Code, as applied by Dr. Britton, 

 on logical grounds, sustains their use ; three other names should be 

 struck out : Calijstegia K. Br., placed now in Convolvuhis L. ; 

 Taraxacum Wiggers, held as against Hedypnois Scop, but put by 

 Dr. Britton in Leontodon L., of which name it is the historic 

 application ; and Haplopappas Cass., concerning the delimitation of 

 wdiich is little agreement. This leaves 43 cases of divergence between 

 the usage of the two schools. 



Let us inquire next into the size of these 43 genera, whose names 

 have been excepted from the rule of priority. How many are 

 credited with over a hundred species ? There are only two — Teplirosia 

 Pers. and Desmodium Desv, Teplirosia is retained as against the 

 Linnean Cracca, but surely followers of the International Rules 

 should carefully reconsider the wisdom of replacing a genus-name 

 dating from the first edition of the Species Flantarum ; Desmodium, 

 I agree, is a fit candidate for nomen conservandum. There are but 

 three other genera credited each with 50 or more species, so that 

 it becomes obvious what a small list of exceptions to the rule of 

 priority our conq)romise calls for ! 



i2 



