Three Shale-slope Plants in Maryland 



Edgar T. Wherry 



At a number of places in the Appalachians, between northeast- 

 ern Tennessee and central Pennsylvania, argillaceous rocks of 

 Devonian age (or rarely of other geologic ages) outcrop on the 

 flanks of ridges, and weather into slabs and chips, which slowly 

 slide down hill, so that little or no soil can accumulate (see figures). 

 Only plants which are adapted to withstand exceptionally dry. 



'- ^ — 



Tri folium virginicum Small, on a typical shalc-slopc at Gilpin, Allegany 

 County, Maryland, May 30, 1928. Edgar T. Wherry, photo. 



sterile, and unstable conditions are able to colonize .such "shale- 

 slopes," and many of the species represent \ari(His types of endem- 

 ism. Some of these shale-slope endemics were discovered around 

 1800, and others about a century later, the typical occurrence on 

 Kates Mountain, near White Sulphur Springs, West Mrginia, 

 having been particularly fruitful at the latter period. As, however, 



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