260 Nichols: The vegetation of Connecticut 



For while, like the willow, the cottonwood is relatively intolerant 

 of shade, it grows more rapidly and to a much larger size, so that 

 it tends to overtop and shade out the willow. Meanwhile other 

 trees make their appearance. In addition to the species already 

 enumerated, common trees on the Connecticut River flood plains 

 are the elm (Ulmus americana), silver maple {Acer saccharinum) , 

 basswood (Tilia americana) , white ash {Fraxinus americana) and red 

 ash {Fraxinus pennsylvanica) . Without exception, all of these last- 

 named trees are more tolerant of shade than their predecessors. 

 Springing up in the light shade which the cottonwood and willow 

 produce, these more tolerant species become increasingly abundant 

 until ultimately they dominate the forest. And while today the 

 cottonwood and willow are perhaps the most conspicuous trees 

 of the Connecticut River flood plains, there is little doubt that the 

 forests which originally clothed the higher flood plains were made 

 up largely of elm, silver maple, basswood, and ash. 



A striking feature of the vegetation in flood plain forests is 

 the wealth of lianas. Woody forms, such as Rhus Toxicodendron, 

 Vitis vulpina, and Psedera quinquefolia, ascend the trunks of 

 trees and hang in graceful festoons from the branches. A few 

 herbaceous lianas also, notably Sicyos angidatus and Echinocystis 

 lohata, clamber the trees, while numerous less vigorous species, e.g. 

 Polygonum scandens, Amphicarpa monoica, Convolvulus sepium, 

 Solanum Dulcamara, and Clematis virginiana, twine about or cling 

 to any available support. The parasitic Cuscuta ohtusiflora is a 

 common form on the Windsor flood plain. Shrubs are usually few 

 and scattered, about the only forms ordinarily present being Cornus 

 Amomum and Samhucus canadensis. 



The herbaceous undergrowth in such a forest is rank and 

 luxuriant; some idea of its character is conveyed by Fig. lo. 

 Tall, broad-, thin-leaved mesophytic plants predominate. The 

 giant ragweed {Ambrosia trifida) commonly reaches a height of 

 from ten to twelve feet, and the ostrich fern {Onoclea Struthiopferis) , 

 largest of the native ferns, a height of more than six feet. The 

 nettles {Laportea canadensis and species of Urtica), growing more 

 than waist-high, are uncomfortably abundant. Other charac- 

 teristic herbaceous species worthy of mention are the follow- 

 ing: 



