IOWA ACADEMY OF SCIENCES. 173 



Populus monilifera, Rhus glabra, 



Salixhumulis, Rosa blanda yar. Arkansana, 



Tilt a Americana, Uhnus fulva, 



Ulinus A^nericana , Querctis macrocarpa, 



Fraxinus pubescens, Crataegus mollis, 



Celtis Occident alis , Populus monilifera, 



Prunus Virginiaita, Ostrya Virginica, 



Ribes gracile , Vitis riparia, 



Celastrus scandens, Ampelopsis quinquefolia . 



Near the edges towards the top of the ravine, 



Salix humilis, Salix atnygdaloides, 



Amorpha canescens, Symphoricarpos occidentalis . 



The Sijniplioricarpos occidentalis is the most abundant 

 shrub in clearings, and on the hills is one of the most 

 important plants in preparing the soil for a mesophytic 

 forest. It remains as an undergrowth in the forest till the 

 trees have attained an age of ten to fifteen years. It is 

 abundant in all open clearings in the woods. This plant 

 takes the place of Cor/jlus Americana to a large extent in 

 preparing the soil for a forest growth. Corylus Americana 

 is rather a rare shrub. The Rhus glabra is nearly as 

 important as Symphoricarpos. From the ravine the meso- 

 phytic flora extends to the slopes of hills, especially on the 

 east and north slopes. The more important mesophytic 

 herbaceous plants in the ravines are — 



Dicentra cucullaria, Parietaria Pennsvlvanica, 



Eupatorium ageratoides, Teucriutn Canadense, 



Lophanthus scrophularicefoHas Viola pubescens , 

 Viola palmata var. cucullata. 



As the ravines become older with a good covered humus 

 and sufficient shade, the following plants are abundant: 



Stnilacina stellata, Viola pubescens, 



Viola pahnata var. cucullata, Vicia Americana, 



Aquilegia Canadensis , Arabis hirsuta 



Mosses like Hypnutn and Bryum. Eupatorium ageratoides . 



Sanicula Marylandica Ranunculus abortivus , 



Hydtophyllum Virginicutn, Phlox divaricata, 



Cystopte-is fragilis, Stnilax herbacea, 



Bromus purgans , Laportea Canadensis, 

 Aster sa^ittifolius . 



The older ravines with a truly mesophytic flora contains 

 a curious assemblage of southern plants that in the Missis- 



