330 



Minnesota Plant Life. 



modified into a defensive armor. These plants indicate a strong 

 adaptation to desert life. Their massive, leafless stems leaf- 

 less in the sense of producing no ordinary foliage leaves sug- 

 gest the scantiness of the soil-moisture which they are able to 

 absorb, and because it is so- hard to obtain, they have abandoned, 

 as far as possible, their evaporating surfaces. Some of them, 

 like the melon-cacti, have not only lost their foliage, but have 

 shortened their stems into spherical or ovoid melon-shaped 

 bodies. They have large roots, usually extending to a con- 

 siderable distance in all directions from the base of the stem. 



The strong defensive armor of 

 spines, which most varieties 

 possess, suggests a danger to 

 which the plants of an arid 

 region are exposed, owing to 

 the absence in such districts of 

 abundant forage for herb-eat- 

 ing animals. The three Min- 

 nesota species of prickly-pear 

 are all of them wanderers from 

 the southwestern plains, where 

 they developed their peculiar 

 characters, and now that they 

 have entered the more favor- 

 able northern region they re- 

 tain the organization best 

 adapted to their original home. 

 After They are not infrequent in the 

 Minnesota valley, on ledges of 



rock near New Ulm and Redwood Falls. One variety occurs 

 at Taylor's Falls, in the valley of the St. Croix, while two are 

 abundant on the rocks in Pipestone county, in the vicinity of 

 the old Indian quarry. Perhaps the Indians have had some- 

 thing to do with their introduction from the southwest. The 

 three species may be distinguished by their spines and fruits. 

 The western prickly-pear produces a fleshy edible fruit, free 

 from spines, from one to two inches long, shaped somewhat like 

 a pear, borne upon the flat, sinuous joints of the stem. In this 

 variety the spines on the stem are not numerous. They occur 





