1G2 



THE PLANT LIFE OF MARYLAND 



Oak-Gum Association. — On the necks of land stretching south- 

 cast from Baltimore and Harford counties occur tree assemblages 

 to which the above name is given. These "necks" resemble in a 

 general way the peninsulas stretching in a similar direction from 

 Charles and St. Mary's counties, but the difference in vegetation 

 of the two regions seems sufficiently striking to necessitate separating 

 them. To begin with, this association shows a greater number of 

 oaks than does any other. White Oak is dominant though Sweet 

 Gum is almost equally abundant, while Chestnut Oak, Willow Oak, 

 Black Oak and Swamp Oak are more numerous here than they 

 are in any other situation. In marked distinction to the "Meadow," 

 Chestnut is frequent, even on low ground, while Hickories, Maple 

 and Black Gum also occur plentifully. On the other hand there is 

 but little Pine, Cedar or Holly. An examination of the soil map 

 shows that the areas in question do not consist of Meadow, but of 

 Sassafras loam, and the mechanical analysis of the two differ to a 

 certain extent, as the following comparison shows: 



Mechanical Analysis.* 



Meadow, 

 St. Mary's Co. 



2-lm/m 

 Ti- 



ll. 25-0. lm/m (i.l-0.OSm/m 0. 115-0. 0U5m/ n 



0.1 105-0.0001 m/m 

 9.58% 



*From Reports of C. S. Bureau of Soils for 1900 ana 1901. 



The most noticeable difference in the two soils is the relative 

 amounts of medium and coarse sand. The greater proportion of 

 these in the Sassafras loam ensures better drainage, which may 

 account for the greater abundance of Chestnut, Hickory and Tulip- 

 Tree. 



River Swamps. — These correspond in general to the flood plain 

 of the rivers, and accordingly have a soil derived from the periodic 

 deposit of sediment by the river. They vary greatly as to water 

 content, not only among each other but in the same swamp at dif- 

 ferent times of year, and in different parts of the swamp, hence con- 



