4 INTRODUCTION 



country, notably in Columbia, and Dutchess counties in New York, 

 Sussex Co. in New Jersey, and some parts of Connecticut and 

 Pennsylvania. While it is true that these peculiar limestone out- 

 crops maintain a characteristic flora, it is doubtful if there are any 

 species of plants endemic upon them. The limestone thus appears 

 rather as maintaining an aggregate of characteristic species than 

 as definitely controlling the distribution or evolutionary history 

 of any particular species. I think there is no species in our area 

 that has been collected only on limestone, but many that seem to 

 predominate there, notably some Crataegus, Amelanchier, sedges, 

 Camptosorus, Asplenium, and a few others. 



7. The glaciated part of our range contains many ponds, 

 swamps, and bogs and it is the latter that are of chief interest 

 to the botanist. These undrained areas, usually, though not al- 

 ways, deficient in lime, and exhibiting a high degree of acidity, 

 maintain a flora quite characteristic. It has been shown that 

 that section of our area which was neither glaciated nor on the 

 coastal plain does not contain the plants characteristic of the 

 glacial bogs of the north and also found in the typical cranberry 

 bogs of the coastal plain. It is certainly true that bogs are un- 

 known in this region (see map, pi. 2), and that it contains no lakes 

 or ponds of any size. It is significant that the following plants 

 are found in the bogs of the coastal plain, mainly in the pine- 

 barrens, and also north of the moraine, but unknown in the inter- 

 vening unglaciated Piedmont Plateau in New Jersey; in Penn- 

 sylvania further study is necessary on this point. 



Chamaecyparis thyoides (see pi. 6), Blephariglottis cristata, 



Panicum linear if olium, Blephariglottis blephariglottis, 



Carex trisperma, Arethusa bulbosa, 



Car ex Collinsii, Sarracenia purpurea, 



Xyris Congdoni, Drosera intermedia, 



Helonias bullata, Oxycoccus macrocarpus, 



Gyrotheca tinctoria, Aster spectabilis. 



There are many others,* and future studies may be able to show 

 that there is some other reason for the non-occurrence of these 

 plants than the failure of this unglaciated area north of the 

 coastal plain to develop bogs and ponds. 



* Harper, R. M. Coastal plain plants in New England. Rhodora 7: 69-80. 1905. 

 Rhodora 8: 27. 1906. 



