Vol. 5 No. 9 



TORREYA 



September, 1905 LIBRARY 



NEW Y0;j4C 



URKilN UF RHUS BIPINNATA 



Hv Kdwaki) L. CJkeknk 



BO( AN'!'A|. 



From the annals of botany and of horticulture a list of some 

 length might be made of so-called varieties of trees and shrubs, 

 each differing from its specific type by more or less deeply cut or 

 cleft leaves or leaflets ; and the varietal name iaciiiiata, by the way, 

 is almost uniformly employed to designate this kind of morpho- 

 logical aberration. One meets with it in genus after genus, and 

 it is found associated with the mutations of more than one spe- 

 cies witliin the same genus, as in the case of R/iiis, when we have 

 Rli/ts ^i^-iabra laciniata, and an earlier R/ins typliiiia lacininta. 



Heretofore this not unusual type of variability has not seemed 

 significant to botanists, if one may judge b}' the brief and slight- 

 ing allusions made to them in our books of botany, where they 

 are apt to be treated as if not deserving varietal names ; so that 

 for any even half-adequate account of them one must consult 

 books or journals of horticulture — this even in the case o{ Rliiis 

 bipitiiiata, which originated not under cultivation, but was found 

 wild in the woods of eastern Pennsylvania ; a shrub so widely at 

 variance with its nearest allies that the finder did not even guess 

 it to be a Rhus at all. 



In the light of the mutation theory, newly advanced and 

 already meeting with wide acceptance, the class of morphologic 

 deviations to which this '[m-\c sumac belongs attains a new sig- 

 nificance. Every such plant deserves from systematic botany 

 better treatment than that of being passed by without a name. 



In the heading of these notes I shall seem to have promised 

 an account of the origin of the form under consideration. Hut 

 my meaning is rather to indicate how far we are from knowing 

 how the shrub originated ; hoping, however, to incite those living 



[No. S, Vol. 5, of ToKKK.VA, comprising pages 135-154. was issued August 26, 



1905.] 



155 



