167] FLORA OF COLUMBIA AND VICINITY 25 



If the banks are low and moist, the herbs belong to the limose 

 and palustrous associations ; if they are high and dry, the herbs 

 belong to mesophytic types. There are five riparian associa- 

 tions, of which the first is primary: 



a. Ripariae salicoides. The willow association of 

 trees and shrubs is the most characteristic riparian plant-group. 

 Only the shrubby willows grow in close formation, the others 

 being often separated by wide intervals. Here occur the larg- 

 est trees, the sycamore, Platanus occidentalis, and the cotton- 

 wood, Populus monilifera, often attaining a diameter of four 

 feet and more, but arborescent and fruticose species are more 

 common. The following species are characteristic: 

 Juglans cinerea Quercus platanoides 



Carya amara Ulmus fulva 



Populus monilifera U. racemosa (local) 



Salix nigra U. Americana 



S. longipes Celtis occidentalis 



S. amygdaloides Morus rubra 



S. longifoha Platanus occidentalis 



S. cordata Acer dasycarpum 



S. Missouriensis A. Negundo 



Carpinus Carolinianus A. nigrum 



Ostrya Virginica Aesculus glabra 



Betula nigra Fraxinus lanceolata 



Alnus serrulata (rare) 



b. Ripariae vitoides. The grape association of trail- 

 ing and climbing plants is best developed on high moist banks, 

 though trees burdened with them are frequent in all situations. 

 The best examples of bank-lianas occur along Hinkson creek 

 southwest. The principal plants are : 



Clematis Virginiana (rare) Celastrus scandens 

 Menispermum Canadense Vitis cinerea 



Rlius Toxicodendron V. cordifolia 



