LAKE BLUFF, RAVINE, AND RIVER VALLEY 



267 



the moist sides of the ravines. Polygyra clausa and P. thyroides 

 are the most common in the ravines. 



The clay ravine presents a slope on which the most char- 

 acteristic trees are the water beech and hop hornbeam, while 



Fig. 408. — Wild hydrangea, Hydrangea arborescens, in French Canyon, 

 Starved Rock. 



witch-hazel is likely to be the dominant shrub. Hepatica, 

 bloodroot, meadow rue (Fig. 399), wood betony, Prenanthes, 

 and maidenhair ferns are likely to be common on the lower por- 

 tions of the slopes. More xerophytic forms, such as wild sar- 

 saparilla and false Solomon's seal, are found on the upper slopes, 

 while on the bottom, especially if a flood plain is developing, 



