27 



for the occurrence of only four woody forms out of a total endemic 

 element of 22 species, disproves this contention. Nor do anti- 

 quity or woodiness prevail among the species of endemic genera. 



Rarity or commonness do not appear to have much to do with 

 the age of our local endemics. For it has been shown that some 

 of our most widely spread species are among the newest in point 

 of origin. Speed of distribution, may be, and usually is, con- 

 trolled by factors with which the origin of an endemic has 

 nothing to do. 



Relict endemism accounts for five of the local species which 

 are shown to be outpost survivals of a preexisting flora. All of 

 these are species of endemic genera; only one is woody although 

 these are probably the most ancient of all our endemics. 



Generic and specific instability seems to account for the great 

 majority of our endemics, 14, in all. These species are all 

 shown to belong to genera that dwindle, or to be related to species, 

 that are on or near their limits, in the local region. Further 

 support of this view is given by the proportion of species in 

 eastern North American genera containing endemics, to the 

 number of species found in the rest of the country and abroad. 

 It was also shown that while only 20 per cent, of our whole 

 vegetation finds its limits in the area, much over half of our 

 total endemics belong to genera that dwindle, or are related to 

 species that find their limits, here or very near here. 



"Habitat endemism," where a species seems to have been 

 thrust off from a well known and widely dispersed form, into 

 a totally different habitat from that of the supposed progenitor, 

 seems to account for two of our local endemics. And one other 

 is anomalous. 



Endemism seems, then, to be a quality in the making of which 

 many forces are operative. It may not always be possible to 

 say as to just what is to be attributed the origin and succesful 

 spreading of any particular endemic. The various tendencies, 

 outlined above, seem to shape themselves from a study of the 

 local species, but it may be found that the principles here set 

 forth must be modified when they are applied to other and 

 wider fields. 



Brooklyn Botanic Garden 



