34 UNIVERSITY OF MISSOURI STUDIES [176 



trees. In the first type, which represents the alluvial forest of 

 the central United States, trees nearer akin to those of the maple 

 timberlands than to the trees of the oak openings prevail, in the 

 other the lowland oaks are dominant. 



a. AUuviales tilioides. The basswood association of 

 bottoms' trees occurs in the wooded flats of the streams. The 

 following are the chief trees : 



Juglans cinerea Platanus occidentalis 



Carya sulcata Acer dasycarpum 



C. amara A. nigrum 



Ostrya Virginica A. Negundo 



Ulmus fulva Aesculus glabra 



U. racemosa (rare) A. lutea 



U. Americana Tilia Americana 



Celtis occidentalis Fraxinus Americana 



Morus rubra F. lanceolata 



Asimina triloba F. nigra 



The following lianas are common in the trees : 

 Smilax hispida Quinaria quinquefolia. 



S. rotundifolia Ampelopsis cordata 



Menispermum Canadense Rhus Toxicodendron 



Vitis riparia Campsis radicans 



V. cordifolia 



Sambucus Canadensis is common about the borders of allu- 

 vial woods. 



b. AUuviales quercoides. The swamp oak association, 

 consisting of Quercus palustris and Q. platanoides as primary 

 and Q. macrocarpa as secondary timber trees, occurs mainly in 

 the low plains north, but there is a creek bottom east covered 

 quite wholly with Q. platanoides. The floor of these forests 

 has the usual lowland vegetation. 



