BIG SPRING PRAIRIE. 73 



quefolia (Virginia Creeper); Rhus radicans (Poison Ivy); 

 Staphylea trifolia (Bladdernut); Sambucus canadensis 

 (Elderberry); Lonicera (sp?) (Honeysuckle); Spiraea 

 (sp?); Viburnum (two species) (Arrow wood); Mains 

 coronaria (American Crab-apple); Salix (several spe- 

 cies) (Willows); Populus deltoides (Cotton wood); Pop- 

 ulus tremuloides (Trembling Aspen); and Cornus flori- 

 da (Flowering Dogwood). In all there are twenty-five 

 or more species, some forming a sort of zone along the 

 edge of forest. 



On West Dune only the following eight shrubs and 

 young trees were observed: 



Euonymus atropurpureus (Wahoo); Euonymus 

 obovatus (Running Strawberry); Viburnum prunifolium 

 (Black Haw); Rubus villosus (Common Blackberry); 

 Cornus stolonifera (Osier); Parthenocissus quinquefolia 

 (Virginia Creeper); Vitis sp? (Wild Grape); Populus 

 tremuloides (Trembling Aspen.) 



The Dune Complex, being richer in genera and 

 species, indicates conclusively its priority in formation. 

 Perhaps the West Dune was formed when there was 

 only a lake remnant, and there was not the same op- 

 portunity for the transportation of suitable seeds by 

 water currents, as there was in the case of the Dune 

 Complex. It would also indicate that the seeds were 

 introduced upon the Dune Complex by water currents 

 rather than by wind dispersal, or else the disparity in 

 number of genera and species upon these two dune 

 areas would not be so great, as they are only a short 

 distance apart. 



If the prevailing westerly winds were the chief 

 factor in the introduction of new species in this region, 

 the West Dune ought to be much richer in species than 

 it is, as for many years past, it must have intercepted 

 the seeds from this source. Perhaps this accounts for 

 the greater abundance of Cottonwoods on the West 

 Dune. 



