I04 REPORT OF NEW JERSEY STATE MUSEUM. 



To argue that the same plants will appear wherever suitable 

 soil conditions are present implies that the seeds of all plants are 

 constantly being scattered broadcast, which is certainly not the 

 case, or we should have no trace of the very evident agreement 

 between plant distribution and climatic life zones. • 



The matter of seed distribution by birds has, I think, been 

 greatly exaggerated, and I doubt if birds exert any appreciable 

 influence upon plant distribution except in cultivated areas. 



Robins, for instance, devour vast numbers of wild cherries in 

 western New Jersey and along the coast, and must scatter the 

 seeds far and wide. The birds are frequent over the Pine Bar- 

 rens, and must scatter cherry stones there as well as elsewhere, 

 and yet the wild cherry is unknown there except in a few isolated 

 cases in cultivated spots. On the untouched floor of the sandy 

 pine woods the cherry' stones fail to germinate or to take root, 

 but once the ground is cleared and the soil is turned by the plow 

 conditions are changed. 



Turning now to the consideration of the coastal plain flora of 

 New Jersey, we realize that many plants of the more elevated 

 country to the north and west have spread southward and east- 

 ward into the coastal plain, mainly along its western border, 

 wherever soil conditions were favorable for their support, and 

 have replaced or mingled with the more austral flora that prob- 

 ably originally covered the whole of southern New Jersey, so 

 that in certain sections this element furnishes a considerable 

 portion of the total plant life. 



As has already been stated, there is also to be found in the 

 Piedmont region an element of the more southern flora of the 

 coastal plain, though not so great in extent as that which this 

 region contributes to the coastal plain. Whether these plants 

 have spread westward from below the fall line or whether they 

 are remnants of a similar flora to that which now covers the 

 coastal plain, and which has been all but superseded in the Pied- 

 mont region by the more advanced flora now found there, is a 

 question hard to solve. 



Two main causes seem to be active in governing the distribu- 

 tion of plants — i. e., climate and soil conditions. Climate, we 

 may say, determines what species are able to exist in a certain 



