300 THE PLANT LIKE OF MARYLAND 



forest of the summits of the gravel hills of the Lower Midland Dis- 

 trict and their bases (see p. 217), or in the identity of forests in 

 like topographic situations on Cecil loam or on Cecil clay in the 

 same District (see p. 202). And again, widely distinct soils in 

 different localities may display the same plant covering. On the 

 Susquehanna gravel of Cecil County and on the loams derived 

 from Devonian shales on Piney Mountain in Allegany County may 

 be seen identical forests of Chestnut and Chestnut Oak, with 

 the same accompanying shrubby and herbaceous vegetation. It ap- 

 pears then that forest types do vary with the underlying soils when 

 these are of marked character, but that they also do not fail in many 

 cases to be uniform over different soils, and to vary on the same 

 soil. In how far these results are due to the forest areas examined 

 being almost exclusively second and third growths cannot be de- 

 termined. 



There are certain trees the presence or absence of which may be 

 taken as valuable evidence in judging soils, even in the present dis- 

 turbed condition of the forests of Maryland. Several classes of 

 soils which are thin, rocky or gravelly and several classes of topo- 

 graphic situations in which the conditions are equivalent are found 

 to abound in the Chestnut Oak, the Post Oak, the Black Jack Oak 

 and the Scarlet Oak. The predominance of any one or two of these 

 trees, for they rarely all occur together, may be taken as a clear 

 indication that the soil is not suited for any of the usual farm crops, 

 although a few fields of buckwheat have been seen on such soils, 

 and near such forest stands in the Mountain Zone. In similar 

 fashion the occurrence of the Swamp Oak may be taken as a sure 

 indication of poorly drained and sour soil, demanding underdrain- 

 age for successful cultivation. For the growth of specialized crops 

 the indications to which these trees point may be in the opposite 

 direction. On the Eastern Shore the occurrence of the Black Jack 

 Oak is an indication of a sandy or light loam soil with excellent 

 drainage, which would promise success with small fruits, berries, 

 watermelons, sweet potatoes or peanuts. The occurrence of the 

 same tree in the Mountain or Midland Zones, however, would have 

 no such significance, for the rocky barrens in which it is most com- 

 mon, as for example the Serpentine Barrens in the vicinity of Dub- 



