A NORTHERN PRICKLY PEAR 



211 



make comparisons with other collections now growing here from 

 Texas and Kansas." 



Since the isothermal lines in western Canada take a southeast- 

 northwest direction, this locality should mark what is physically 

 perhaps the most northern outpost known for any cactus.' Yet 

 cacti are b}^ no means rare in Canada, for Palliser saw sage brush 

 and cactus on the bluffs of the South Saskatchewan, and Macoun 

 and other travellers found the same and other arid land plants 

 abundant in the valley of the Red Deer River in southern Alberta, 

 growing on cretaceous clay. Macoun, in his Manitoba and the 

 Great Northwest, writes of his travels in southwestern Saskatche- 

 wan, some 200 miles south of this place, as follows: "For 30 miles 

 west of Moosejaw Creek the country was very dry, and frequent 

 sand and gravel hills were seen with occasional patches of cactus, 

 Opuntia missouriensis, where the surface was sandy." Again he 

 states regarding the region south of the present city of Moosejaw: 

 "Nearly 20 miles over a perfectly level plain, which in places was 

 covered with a profusion of cactus, brought us to the base of the 

 ^Missouri) couteau, at a point near the Cactus Hills. The plain 

 between the creek and the hills was principally cretaceous clay, 

 and occasional patches of it were without any vegetation except 

 that peculiar to arid soil." The soil on which the North Battle- 

 ford plants grow is a hard clay which may prove to be an outcrop 

 similar to the clay above mentioned, and a part of the Cretaceous 

 Beds of Dawson's Boundary Survey. It is probable that much of 

 the cactus mentioned by Macoun is this prickly pear. It is clear 

 that the plant is found both on sands and cretaceous clays, either 

 in one or more specific forms, and that it is almost or quite absent 

 on the rich prairie soil composed of glacial drift. 



Another cause for the presence of this far northern colony may 

 be the fact that it nestles on the southwest side of the bluffs skirt- 

 ing the river, where it receives the fullest possible benefit of the 

 sun's rays. The primary cause, however, may lie bcliind the fact 

 that it is found in one of the numerous buffalo \\ ;iilows. It is 



'^The northernmost locality recorded for any species of cacni-* is in latitude 

 56° 12', on the banks of the Peace River, where Macoufi found Opunlia 

 ■ ynissouriensis. — Ed. 



