NICHOLS: THE VEGETATION OF CONNECTICUT 259 
One of the first trees to establish itself on the flood plain is the 
black willow (Salix nigra). The willow is essentially a pioneer. 
Young flood plain forests (Fic. 9) may be composed almost wholly 
of this tree, while a zone of willow almost invariably fringes the 
shoreward margin of older forests. Closely following the willow, 
in fact often appearing simultaneously with it, are other trees, 
such as the sycamore (Platanus occidentalis) and the cottonwood 
ak 
& 
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aa E 
i ; 
tr 
pid’ 
Fic. 10. Cottonwood forest with luxuriant herbaceous undergrowth (Laportea, 
etc.) on flood plain island at Windsor. 
As the surface of the 
(Populus deltoides), particularly the latter. 
atively 
ground continues to be built up higher, the soil becomes re 
drier and better aerated, so that conditions rapidly become less 
Under the changing condi- 
any 
hydrophytic and more mesophytic. 
tions of soil and light, the willow gradually assumes a position of 
less and less importance, while the cottonwood comes to occupy 
a more and more prominent place in the rising forest (FIG. 10). 
