64 BULLETIN OF THE 



north, but are rather apparent instances of local variation, many 

 species being confined to very limited localities. 



On Mount Washington, a few rods will often give the same plant 

 in bud, flower, and fruit, as a north or south exposure, a precipice, 

 or a snow-drift may retard or accelerate growth ; but on these 

 southern mountains no such difference obtains any more than in 

 the valleys below. 



On this communication Mr. J. W. Powell remarked that the uni- 

 formity in the altitudes of the peaks is a feature resulting from the 

 fact that the general mass out of which they have been carved by 

 erosion possesses a plateau structure. The elevation of that region 

 was distributed in its effects with an approach to uniformity over a 

 wide extent of country, and was unaccompanied by those sharp flex- 

 ings or the protrusions of abrupt mountain cores, which are en- 

 countered in some portions of the Appalachians and other moun- 

 tainous regions. The individual masses and ranges in the Cumber- 

 land region are the work of erosion — the general process of land 

 sculpture acting upon a broad platform, excavating broad valleys 

 and narrow gorges, and leaving the peaks and ridges as cameos — 

 mere remnants left in the general degradation of the whole region. 

 Prof. Powell exemplified the process by citing the Uinta Moun- 

 tains as a broad platform similarly carved by an extensive erosion. 



The following paper was read by Lester F. Ward, entitled — 



FIELD AND CLOSET NOTES ON THE FLORA OF WASHINGTON 

 AND VICINITY. 



[Abstract.*] 



Introductory Remarks. 



This paper has resulted from a suggestion made to the writer in 

 the spring of 1880, by a member of the Committee on Publications 

 of this Society, relative to the need that exists for some special 



*Mr. "Ward's communication presented to the Society only a brief notice 

 of the principal points of a monograph which he had prepared upon the 

 flora of the District of Columbia. In view of the local character of his 

 subject, and of the thorough and commendable manner in which it had 

 been elaborated, the Committee on Communications recommended, and the 

 General Committee authorized, the printing of a very full and copious 

 abstract of the paper, which is given herewith. 



