32 INTRODUCT ON 



Of course some of these are found in the intervening territory 

 between the sandy stretches of northern New Jersey and adjacent 

 New York and the coastal plain. But they are relatively scarce 

 in this intermediate country. 



51. That the distribution of all of the species mentioned in the 

 preceding paragraphs has been controlled entirely by edaphic or 

 historical factors is very doubtful. So many other minor con- 

 siderations, such as methods of seed dispersal, longevity of seeds, 

 the relative percentage of annuals, biennials, perennials, shrubs 

 and trees, and so forth, may have been contributory factors that 

 it would be dogmatic to assign the distribution trends of any one 

 of them wholly to edaphic factors. But it seems as if these earth 

 and water factors have been, on the whole, most active in deciding 

 the general composition and complexion of the vegetation in our 

 area. There are a few species that appear to be endemic in the 

 range, but as to the factors contributing to this endemism nothing 

 is known. The following are the species endemic in the area: 



Amphicarpon Amphicarpon, Hypericum Bisscllii, 



Calamovilfa brevipilis, Ludwigiantha brevipes, 



Savastana Nashii, Kneiffia Allenii, 



Sporobolus Torreyanus, Pyrola oxypetala, 



J uncus caesariensis, V actinium caesariense, 



Uvularia nitida, Dendrium biixifolium, 



Salix squamata, Stachys atlantica, 



Dentaria incisifolia, Eupatorium resinosum, 



Dentaria anomala, Euthamia floribunda, 



Prunus Gravesii, Helianthus Dalyi. 



Hibiscus oculiroseus, Senecio Crawfordii. 



It is of interest to note that of these 22 endemic species, 7 are 

 peculiar to the pine-barrens, 9 to the glaciated region and 6 to 

 the coastal plain, but the latter are not pine-barren species. 

 However, the frequency of occurrence of these endemic species is 

 greater with the pine-barren and coastal plain species than with 

 those of the glaciated region, many of which have been collected 

 only once or twice. As a criterion of endemism in our area the list 

 is open to the objection, of course, that some plants here recorded 

 as species would not be accepted as such by all writers. But as 



