AMERICAN INSTITUTE. 491 



the Chemung group. The wild poplar exists east as far as the 

 Connecticut river but does not cross it. The cotton wood exists 

 as far north as 43^ in the valley of the Genesee, yet is not found 

 in lower latitudes to the east. It is well known that the original 

 flora of the valley of the Mississippi was quite different from that 

 of the Atlantic slope. The buckeye is unknown in the seaboard 

 States, and it is equally true that good butter has never yet been 

 produced west of the Atlantic slope. 



But the selections of soil by trees in limited districts under our 

 immediate observation, are equally noticeable. The chestnut in- 

 habits the loose dry soil of hill sides, while the butternut chooses 

 the rich bottom lands. Where fires have been built, and the sa- 

 line matter thus increased in the soil, the choke cherry springs 

 up; while around the deserted habitations of man in the wilder- 

 ness, briars thrive, and the foetid Jamestown weed finds a habita- 

 tion. So delicate is the relation between the distribution of 

 plants, and the nature of the soil, that where man has once inter- 

 fered, the original distribution is never again restored. 



With change of soil, and consequent change of chemical com- 

 position, there also occurs in plants more or less change of con- 

 stitution. Thus the white pine which inhabits the eastern portion of 

 this continent from Hudson's bay, where it is a mere shrub, to our 

 own latitude, where it sends up a clean stem for eighty feet; 

 thence southward to the southernmost spur of the Alleganies, 

 manifests different physical properties in its wood. In New Eng- 

 land and New- York, it is clear and close grained, with little 

 alburnum^ and known as 'pumpkin pine; while further south, it 

 is more completely composed of sap wood, and worth less for 

 building purposes. The same diiference exists also between the 

 original growth of pine and the second growth^ occurring as it 

 does, on a soil that varies in its chemical constituents from the 

 conditions that attended the primitive growth. " The vegetation 

 of the black gum," says Michaux, " exhibits a remarkable singu- 

 larity. In Maryland, Virginia, and the western States, where it 

 grows on high and level grounds with the oaks and walnuts, it is 

 distinguished by no peculiarity of form. In the lower part of the 

 Carolinas and Georgia, where it is found only in wet places, with 



