PROGRESSIVE AND RETROGRESSIVE CHANGES IN THE 
PLANT ASSOCIATIONS OF THE DELAWARE COAST 
LAETITIA M. Snow 
(WITH SIX FIGURES) 
During July and August 1901, certain observations were made 
on the plant associations of the Delaware coast, from Cape Hen- 
lopen southward, for about six miles.‘ Ten years later, in July 
1911, the same region was again visited in order to ascertain the 
changes which had occurred during the interim. 
Considering the extreme instability of dune topography, 
surprisingly little change was noted, thus indicating the slowness 
with which plant associations, in general, change their character. 
Certain observations, however, seem of value, as indicating the direc- 
tion of change in various associations, and are therefore recorded. 
As in the previous study, on account of the lack of flowers and 
fruit, the identity of many forms was difficult—at times impos- 
sible—to determine. For regions which showed practically no 
change, no lists are presented. Where changes were noted, only 
dominant forms are given, in order that an idea of the direction of 
change may be obtained. The nomenclature of Gray’s Manual 
(7th edition) is used, with the Britton synonyms in parentheses. 
Grateful acknowledgment is due Professor Kart M. WiEGAND 
for his kind assistance in the identification of certain species. 
I. Geography and physiography 
Ms a general discussion of the position, topography, soil, and 
climate of the region was presented in the former paper, a con- 
sideration of these points will be omitted. 
II. Plant formations 
A. TREELESS OPEN 
1. Beach formation—(a) Lower beach——-The contour of the 
lower beach varied exceedingly during July 1911, thus indicating 
t Snow, L. M., Some notes on the ecology of the Delaware coast. Bor. Gaz. 
34: 284-306. map and figs. I-Io. 1902. 
45] [Botanical Gazette, vol. 55 
