26o A NATURALIST IN THE GREAT LAKES REGION 



soil water drains out so readily. They are exposed, too, to the 

 cold winds from the lake. It is to be expected, therefore, that 

 the plants, especially of the crest, will be xerophytic and hardy 

 (Fig. 389). White pines, jack pines, cotton wood, large- and 

 small-toothed aspens, red cedar, white birch, spreading juniper, 

 leatherleaf, red-osier dogwood, glaucous willow, and staghorn 

 sumac are the characteristic shrubs and trees on those bluffs 

 that are somewhat stabihzed. Sweet clover and many other 

 common weeds that can stand severe exposure are found, such 





K^ 





Fig. 389.— Lake shore bluff with xerophytic vegetation 



as mullein, Canada thistle, dock, Russian thistle, the horsetails, 

 Equisetum hyemale (Fig. 390), and E. arvensis. 



The animal life is scant but is as distinctive as the plant. As 

 in the Dunes we found a tiger beetle, characteristic of nearly 

 every zone, so here we find Cicindela purpurea limhalis (Fig. 145) 

 confined to this particular habitat, chiefly on the wet clay bluffs. 

 The holes of the larvae are common on bare spots, and the 

 adults are abundant in midsummer, hunting over the sparse 

 vegetation for insect prey, particularly the sweet clover. The 

 clay-bank spider, a large black one, Pardosa lapidicina (Fig. 391), 



