26 



tion rather than near the center. Certainly nearly all our local 

 evidence points that way, and on a much wider scale, the dis- 

 tribution of the genera which happen to contain local endemics, 

 further supports the argument. If this is correct, it will be seen 

 that endemism may have little to do with woodiness or antiquity; 

 indeed, as we have seen, it does not seem to bear much relation 

 to either of these qualities in our local area. Nor may it have 

 much to do, either, with rarity or commonness, for it has also 

 been shown that these questions relate to the subsequent per- 

 formance of endemics rather than to their origin. The powers 

 of adaptation, which must be the measure of the capacity to 

 spread, differ so widely and are influenced by so many factors 

 with which endemism has confessedly nothing to do, that the 

 use of the rarity or commonness of any particular endemic as a 

 criterion of its age is likely to lead to grave error. 



There are still three more endemic species in the local flora 

 area that have not been accounted for. In some ways they are 

 the most puzzling cases of the lot, for they do not seem to be in 

 the category of their fellows. In the case of two of them they 

 might be called "habitat endemics." Prunus Gravesii is ob- 

 viously a rock-loving offshoot of the predominately sand-inhabit- 

 ing and widely dispersed P. maritima. This curious form has 

 only been found at one locality, on a rocky ledge, where the 

 difference between its habitat and that of its probable progenitor 

 is very marked. The other habitat endemic is Savastana Nashii, 

 which is the only salt-marsh species of the genus known in the 

 area. The inference that it has been derived from the closely 

 related S. odorata is obvious. In fact there are taxonomists 

 that doubt the specific validity of this endemic at all. About 

 the third and last of our local endemics little is known, either of 

 its origin or of the causes of that origin. There seems, in this 

 case, so little collateral evidence that one is almost glad to record 

 merely its name, Dentaria anomala! 



Summary. 

 Endemism, as found in the flora of the vicinity of New York, 

 does not appear to be a criterion of antiquity, for many endemics 

 are very recent. Neither are the endemics prevailingly woody, 



