172 BOTANICAL GAZETTE [MARCH 
C. The active or wandering dunes. The dune complex.—The 
stationary embryonic dunes on the beach begin to wander as 
soon as the conditions become too severe for the dune-forming 
plants. The first result of this change is seen in the reshaping 
of the dune to correspond with the contour of a purely wind- 
made form. The rapidity of this process is largely determined by 
the success or failure of the dune-formers as dune-holders. The 
best dune-holders are Calamagrostis, Ammophila, and Prunus. 
There are all gradations between a simple moving dune and 
a moving landscape; the latter may be called a dune-complex, 
The complex is a restless maze, advancing as a whole in one 
direction, but with individual portions advancing in all directions. 
It shows all stages of dune development and is forever changing. 
The windward slopes are gentle and are furrowed by the wind, 
as it sweeps along; the lee slopes are much steeper. The only 
plant that flourishes everywhere on the complex is the succulent 
annual, Corispermum hyssopifolium, although Populus monilifera is 
frequent. The scanty flora is not due to the lack of water in the 
soil, but to the instability of the soil and to the xerophytic air. 
The influence of an encroaching dune upon a preexisting flora 
varies with the rate of advance, the height of the dune above the 
country on which it encroaches, and the nature of the vegetation. 
The burial of forests is a common phenomenon. The dominant 
forest trees in the path of advancing dunes are Pinus Banksiana 
and Quercus coccinea tinctoria. These trees are destroyed long 
before they are completely buried. The dead trees may be 
uncovered later, as the dune passes on beyond. 
In the Dune park region there are a number of swamps upon 
which dunes are advancing. While most of the vegetation is 
destroyed at once, Salix glaucophylla, S. adenophylla, and Cornus 
stolonifera are able to adapt themselves to the new conditions, by 
elongating their stems and sending out roots from the buried 
portions. Thus hydrophytic shrubs are better able to meet the 
dune’s advance successfully than any other plants. The water 
relations of these plants, however, are not rapidly altered in 
the new conditions. It may be, too, that these shrubs have 

