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 (Fig. 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 {Plataniis occidentalis) and the cottonwood 



Fig. 10. Cottonwood forest with luxuriant herbaceous undergrowth {Laportea, 

 etc.) on flood plain island at Windsor. 



(Popiihis deltoides), particularly the latter. As the surface of the 

 ground continues to be built up higher, the soil becomes relatively 

 drier and better aerated, so that conditions rapidly become less 

 hydrophytic and more mesophytic. Under the changing condi- 

 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). 



