PAPERS ON BOTANY 123 



There is also a small red bristled opiintia peculiar to 

 Ohio, which in the near future is very likely to be recog- 

 nized as a species. 



Regarding- the great quantity and variation in these 

 plants in the southwest, Botanists of recent years have 

 shown an inclination for defining every type into a species. 

 The writer can hardly agree with either this idea or the 

 idea of referring all near related to one species. The pre- 

 vailing specific requirements should be adhered to in this 

 class of plants the same as in all others. We are all 

 familiar with the vast variations in our cultivated apple. 

 Several types of well marked fruits ; color of bark both on 

 old trunks and twigs, also difference in color of the leaves. 

 But they are all of one species and no Botanist would 

 think of dividing it into as many species as there are even 

 decided variations. Xeither would we think of referring 

 the apricot to the peach or plum on the supposition that it 

 Is a hybrid between the two. 



In prunus Pennsylvanica and P. scroflna we have much 

 less difference in the trees and leaves than we have in some 

 of the forms of the apple and tlieir specific difference is 

 chiefly in their mode of flowering and fruiting. 



We would therefore suggest that by applying the same 

 methods to the opuntia as is applied to other plants, and 

 basing their specific status on definite characters it is no 

 question but wdiat these plants can be defined and under- 

 stood as accurately as any other. 



As an illustration, 0. Ivptocnrpa was established by 

 Mackensen by its fruit, still the plant itself is more definite 

 than the fruit. Experiments by B. R. Russell, San Saba, 

 Texas, developed that ten cuttings from the same plant 

 produced six forms of fruit, but all the plants retained the 

 resemblance of the parent. 



Many instances of confusion among recent botanists are 

 also evident, many of which can be traced by the difference 

 in geographical location while others can be accounted for 

 by the difference in geological conditions. 



We have in Opuntia arizonica, Grifaths, C. N. H. 12 :402, 

 1909, wherein Dr. Rose also states that he had probably 

 recognized this opuntia as a new species, does not occur in 

 Arizona as described. If the specimen in the w^riter's col- 



