468 



Minnesota Plant Life. 



rocks and there pass into a dry, dormant condition, except when 

 the rock is wet \vith rain. In Minnesota a number of pinks, 

 rock-roses, purslanes and Canterbury-bells make their home 

 upon .rocky ledges or shores. Here, too, there are to be met 

 with a variety of ferns, such as the cliff-brakes, the polypody 

 and others. With them may be found numerous grasses, plan- 

 tains, verbenas, evening-primroses, ragweeds, capers, and saxi- 

 frages. Upon such rocky ledges may also be discovered, espe- 

 cially in the northern part of the state, the juniper bushes and 

 the ground-hemlock. Rock-succulents are not common in 



FIG. 230. Growth of hardwood trees upon a rocky island. Northwest angle, I,ake of the Woods. 

 After photograph by the author. 



Minnesota; but the prickly-pear cactus of Pipestone and the 

 rock purslane of the Minnesota valley, are examples. More 

 often grasses with rolled up leaves, junipers with needle-shaped 

 or scaly leaves, saxifrages with hairy leaves and other adapta- 

 tional types will be present. The larger rock plants, needing 

 more soil for their root areas, grow in crevices and may be 

 found abundantly wherever the rocks have been split and soil 

 has formed in the clefts. 



Moss heaths. Another class of xerophytic vegetation in- 

 cludes the moss heaths. These are dry, moss-covered stretches. 



