344 



Introduction to Botany. 



plants can accumulate food and produce seeds. Kjellman 

 says of the close of the growing season : " An arctic land- 

 scape at the advent of winter is most nearly like a southern 

 region which has been desolated by a heavy frost before 

 its season. Many plants are interrupted at the height of 

 their growth and stand with frozen 

 lifeless leaves, with swelling flower 

 buds, with half-open or entirely open 

 flowers, and with half or entirely 

 ripened fruit. No preparation has 

 been made for the winter rest; while 

 plants are in full activity, they are 

 paralyzed by the stiffening cold." 

 But how well the plants of this 

 region are able to withstand a catas- 

 trophe that would prove fatal to 

 those of lower latitudes has already 

 been recounted on page 311. 

 It might be expected that the plants of arctic regions 

 would prepare for winter by ripening the new branches 

 and producing protective scales for the young buds ; but 

 yet it seems clear that making the protoplasts, in and of 

 themselves, resistant to the severe cold is the better plan, 

 for the short vegetative period necessitates the rushing 

 forward of the processes of vegetation and reproduction, 

 and affords no time for special defensive preparations. 



As would be expected, growth is very slow in the polar 

 regions; measurements made on the willow, Salix polaris 

 (Fig. 1 86), showed that in most instances, by the end of 

 the growing season, shoots had increased from i to 5 

 millimeters in length, and at most from 5 to 1 1 milli- 

 meters. A forest tree which was 83 millimeters thick 

 at the base was found to have 544 rings of annual 



FIG. 186. 



Salix polaris. Natural size. 

 After SCHIMPER. 



