1903] FLORA OF NORTH CAROLINA 383 
Mrs. Edson» describes the action of a winter storm upon the 
vegetation. The factor in the production of the frost forms 
which weigh down the limbs of trees and snap them off is the 
frozen vapor of the wind and rain. The lower the temperature, 
the denser the cloud becomes; the velocity of the wind and the 
exposure determine the growth of the frost forms. Hence the 
absence of trees is due to the effect of the ice and snow of win- 
ter. This conclusion is strengthened by a study of a recent ice 
storm at Philadelphia, as it damaged large trees that had with- 
stood the storms of centuries. 
In lieu of illustrations to accompany this article, the reader is 
referred to a magnificent volume issued by the United States 
Government," where maps and photographs descriptive of the 
proposed Appalachian National Park are given. 
UNIVERSITY OF PENNSYLVANIA. 
39 Epson, Mrs. HELEN R., Frost forms on Roan Mountain. Pop. Sci. Mo. 
45:30. 1894. 
Forest Leaves 8:168. 1902; also CHAPMAN, Forestry and Irrigation 8: 130. 
1902; Experiment Station Record 13 : 1053. 
4* See Message from the President of the United States transmitting a Report of 
the Secretary of Agriculture in relation to the forests, rivers, and mountains of the 
southern Appalachian region. Senate Document 84: 210. Washington. 1902. 
