PLANTS OF SOUTHERN NEW JERSEY. 99 



NORTHERN ELEMENT. 



Ranging south to N. J. 



From Labrador, 3 



Newfoundland, 4 



Nova Scotia, 4 



Maine, ". 2 



13 



SOUTHERN ELEMENT. 



Plants ranging north to N. J. So. N. Y. Ct. or R. I. Mass. 



From N. Carolina, o o i o 



Georgia, o o i o 



Florida, 4 3 3 13 



4 3 5 13 



LOCAL ELEMENT. 



Massachusetts to Maryland, i 



New Jersey only, I 



WEEDS AND ADVENTIVE VEGETATION. 



Important as is the study of weeds from an economic or 

 ecologic standpoint, they have little or no significance in a geo- 

 graphic discussion of plant life, their principal function being to 

 aid in obliterating all trace of the original range of the native 

 vegetation. 



In the Middle district the woodland, the beds of tide-water 

 creeks and an occasional undrained bog are all that remain of 

 the original vegetation. All the cultivated and waste ground is 

 given over to weeds or introduced plants. 



In the Pine Barrens, however, the great bulk of the ground is 

 still occupied by the native flora, and weeds creep in only where 

 settlements have been established and even then not as abun- 

 dantly as in the Middle district. 



It seems as if artificial interference with the native flora was 

 necessary to the establishment and maintenance of weeds. So 

 soon as the ground is cleared and the sod turned, weeds appear, 

 though previously they Avere unable to gain a foothold. Trafiic 

 along the roads of the Pine Barrens must bring many weed 



