MARYLAND WEATHER SERVICE 159 



in the dense shade produced by the hardwoods the pines do not thrive. 

 The xerophytic oaks such as the Black Jack, Spanish Oak and Post 

 Oak, are largely replaced by White Oak and Black Oak, which here 

 take the lead, accompanied by some Red Oak and several species 

 of Hickory {Hicoria ovata, Hicoria alba and Hicoria glabra). The 

 Tulip-tree is a frequent member of this association, especially on the 

 sloping sides of depressions, where also thrives the Beech. Less im- 

 portant constituents are the Persimmon, the Yellow Locust and the 

 Sweet Gum. While species of oak and hickory and the Tulip-tree 

 frequently form the bulk of a forest, another constituent may form 

 so large a proportion that it almost gives rise to what might be called 

 a distinct association; this is the Chestnut. It prefers well-drained 

 sandy slopes, where it commonly replaces the Tulip-tree of moister 

 slopes. On account of the demand for its timber it is frequently 

 seen as coppice. As an example of a rather xerophytic type of such 

 a forest, the following enumeration is given, referring to a ten- 

 acre tract at Leonardtown, St. Mary's County. The tract bore some 

 evidence of being a part of the original growth, for the trees were 

 of great age; on the stump of an oak recently felled were counted 

 106 rings. The soil was Leonardtown loam, and the general level 

 of the tract was about 80 feet above tide water. The plants seen 

 with their relative abundance was as follows: 



In more mesophytic woods a smaller proportion of the first two 

 oaks and a larger proportion of hickory is the rule. Underneath 

 the oaks, etc., a second zone is usually present, which in the higher 

 areas consists of Dogwood, sometimes as rather large trees, Red 

 Cedar, Sassafras, Holly, Laurel and Sumac (Rhus cupallina. Rhus 

 hirta, Rhus glabra). The humus content of the soil in these woods 



