JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VIII NOVEMBER 4, 1918 No. 18 



BOTANY. — .4 phytogeographical sketch of, southern Maryland. 

 Roland ]M. Hakper, Office of Farm Management. (Com- 

 municated by A. S. Hitchcock.) 



Southern Maryland, according to local usage, is that part of 

 the state between Chesapeake Bay and the fall line, including 

 the counties of Anne Arundel, Prince Georges, Calvert, Charles, 

 and St. Marys, and small parts of a few others. The few bot- 

 anists who have written about this area^ have generally treated 

 it as a geographical unit; but its vegetation is really very diver- 

 sified. Geologists have subdivided this part of the coastal 

 plain in two different ways: first according to the outcroppings 

 of the various Cretaceous and Tertiary strata, and second 

 according to the superficial formations, which are supposed to 

 represent four Pleistocene terraces.^ 



For phytogeographical purposes southern IVIaryland can be 

 divided into five more or less distinct regions, the soil, topog- 

 raphy, and vegetation of each of which vary only within certain 

 limits. Two of them correspond pretty closel}'' with the areas 

 in which certain Cretaceous and Eocene formations are exposed, 

 and another with the oldest and highest Pleistocene (or perhaps 

 Pliocene) terrace. One cannot be correlated very well with any 



1 The most compi-ehensive account is that b}' Chrysler in the Plant Life of 

 Maryland, pp. 149-197 (Baltimore, 1910). 



- These terraces have been discussed at length, with numerous maps, by G. 

 B. Shattuck in his report on the Pliocene and Pleistocene, a separate volume of 

 291 pages and 75 plates published by the Maryland Geological Survey in 1906. 



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