296 THE PLANT LIFE OF M A I: YJ.AXIt 



aeter of a piece of land by the weeds growing on it, — the presence of 

 and abundance of the Great Mullein (Verbascum thapsus) or Sheep 

 Sorrel (Rumex acetosella) , for example, being sufficient to condemn 

 a field as poor, or at least in a "run down" condition. 



Before entering into an examination of the manner in which the 

 common dependence of spontaneous and cultivated plants upon the 

 external factors of climate and soil may cause a relation between the 

 character of the two, it may be well to review the present condition 

 of the vegetation of the state as compared with that which it orig- 

 inally bore, in order to obtain a proper conception of the comparative 

 validity of the several methods of estimating the cultural value of 

 land. 



The occurrence of forest over the state at large is due to those 

 far reaching but fundamental climatic factors, temperature and rain- 

 fall, which are of such a character as to favor this highest type of 

 plant formation throughout eastern North America. Only in the 

 grassy marshes bordering the salt estuaries and in the sands of the 

 coastal bars are local conditions of soil so marked and so hostile to 

 tree growth as to give rise in the former case to a grassland and in 

 the latter to a desert-like condition. Cultivation has replaced the 

 primeval forests with fields and with second and third growths of 

 timber. The difference between a piece of virgin forest and a wood- 

 lot such as may be found on almost every farm, is profound and 

 striking. In the former the largest trees tower to a height of 100 

 feet or more, trees of smaller stature and less demand for light crowd 

 the space between the larger trees, here the shrubby vegetation is 

 sparse and the forest floor darkened by the dense tree-tops above it, 

 in another spot are impenetrable thickets of Rhododendron, Laurel 

 or Bayberry. On the ground or on the fallen trunks of forest giants 

 are dense carpets of shade-loving herbaceous plants or mosses or 

 hepatics. The neighboring wood lot may contain much the same 

 assemblage of trees and shrubs as the virgin growth, but the stature 

 nf the trees is much less and usually the greater openness of the 

 canopy results in a much drier condition of the forest floor with a 

 corresponding alteration in the herbaceous vegetation. The differ- 

 ence between virgin and second growth forests lies, then, not so 

 much in differences in the actual species found in both as in the 



