Alpine and Arctic Floras 



This will explain what is really the chief difficulty of 

 the arctic, and in a less degree of our highland and other 

 alpine forms. Being in sunshine they must, of course, 

 respond to it and set about the work of assimilation. But 

 where is the water to come from ? Roots, stems, and 

 branches are frozen hard, and no water can reach them. 



So surrounded by leagues of frozen water, these 

 wretched plants are actually perishing of thirst. 



The cold itself is by no means so dangerous an evil 

 as this, for, as we have seen, seeds when dry can support 

 an almost unimaginable number of degrees below zero. 

 So arctic plants manage somehow to keep down the 

 loss of water by transpiration. They require but very 

 small amounts of water even in relatively high tempera- 

 tures, as has been shown by actual measurement. 2 



Perhaps one should mention here a strange fact that 

 has been recently commented on by several botanical 

 authorities. In some respects there is a wonderful 

 resemblance between all "open" floras wherever they 

 may occur. Such apparently different associations as 

 these arctic plants, desert plants, others which live above 

 the clouds in the dry cold regions of Tibet and the Andes, 

 marine plants, not only those of salt marshes but of 

 sandy sea-shores, rock " floors " and the like, often show 

 a peculiar and interesting resemblance. 



The explanation seems to lie in the fact that all such 

 floras must do with as little water as possible. In the 

 deserts and above the clouds, simply because there is 

 extremely little to get ; in frozen ground it is not avail- 

 able, and in salt soil it is of so poisonous a character 

 that they reduce their demand for water to a minimum. 



One of the most salient characters of alpine plants is 

 the dwarf, stunted character of most of them. One 

 need only refer to the tiny willows, a few inches high, 

 which represent the genus Salix at great altitudes. 



93 



