NATIVE PLANT GROWTH AS RELATED TO SOILS. 473 



summer by the broom rape (Orobanche minor), which grows as a par- 

 asite on the roots of the clover plants and greatly reduces their vital- 

 ity. Grass meadows, especially of timothy, sometimes contain great 

 quantities of the prickly horse nettle (Solanum carolinense), which 

 considerably reduces the value of the hay. 



Weeds which are largely confined to roadsides and waste ground 

 need not be discussed here, as the more important species have 

 already been enumerated in the description of the plant formations. 



RELATION OF THE NATIVE PLANT GROWTH TO THE CHARACTER 



OF THE SOIL. 



It is known to farmers the world over that in the nature of the 

 virgin growth upon a body of laud they have the best possible indica- 

 tion of its agricultural value. An experienced person can take his 

 stand on a hilltop and, looking off across the country, indicate the 

 quality of the soil hereof there by the forest thai grows out of it. 

 Where he sees a slope covered with a heavy growth of black walnut 

 and yellow poplar (tulip) he knows that the soil will be rich and deep, 

 well suited to wheat. Where tall sycamores and elms flourish on the 

 bank of a stream, there will surely be found fat alluvial soil, the best 

 of all land for growing corn. The Southern planter recognizes prom- 

 ising cotton land by the growth of oaks, dogwood, myrtle, etc., which 

 it bears. 1 On the other hand, he is well aware that a soil which sup- 

 ports only pine, with very little undergrowth, is too sandy and thin 

 to be valuable in its natural state, but, when heavily fertilized, is 

 excellent for forcing early vegetables. 



In a general way such facts as these are known and practically 

 applied wherever the soil is tilled. Little, however, has been done to 

 put this knowledge upon a scientific basis. It would undoubtedly be 

 most helpful to the farmer if he could find out how far the value of 

 this test of uncleared land can be relied upon. He would like to know 

 just how sharp a line can be drawn between soils of different chemi- 

 cal composition, texture, and drainage by carefully noting the wild 

 growth whieh they bring forth. 



It was largely in the hope of being able to throw light upon this 

 problem that the present survey was undertaken. The Dismal Swamp 

 region was selected for the preliminary investigation because it was 

 known that here conditions are less complicated than in many other 

 sections. The evenness of the surface of the Coastal Plain and the 

 absence of abrupt changes of level wo dd naturally tend to simplify 



1 In his Catalogue of the Natural Orders of Plants Inhabiting the Vicinity of 

 the Santee Canal. South Carolina (Proc. Am. Assoc. Adv. Sei., vol. 3, p. 5, 

 1850), H. W. Ravenel writes. "On the highlands bordering these swamps, where 

 the best cotton lands are found, hickories, dogwood (Coriuts florida), oaks, etc., 

 constitute the principal vegetation."" 



