ARCTIC PLANT GEOGRAPHY 151 



The water requirements of arctic plants have not been investigated in 

 a detailed experimental manner by a competent plant physiologist. 

 The scientific conclusions have been based on inference largely, and, 

 if there are detailed pieces of work, they have been done in spots. 

 No comprehensive piece of research investigation on the subject of 

 the source of water and its utilization by arctic plants is in existence. 

 There are many questions that arise in this connection. What is 

 the utilization of rain water by polar species? How do they utilize 

 soil water and what is the source of that water? What is the regime 

 of transpiration or water loss in arctic plants and how is it correlated 

 with internal plant structure and external climatic conditions? What 

 is the temperature range of arctic soils, when underlain by perma- 

 nently frozen soil? What is the relative age of the stunted spruce trees 

 growing in the bottom lands with permanently frozen soil near the 

 surface, as contrasted with the same species on the slopes, where the 

 soil in which the tree roots are found is not frozen permanently? 



Vegetative Growth by Means of Runners 



Holm's "Contributions to the Morphology, Synonymy, and Geo- 

 graphical Distribution of Arctic Plants "^^ is full of reference to the 

 north-south migrations of plants as well as the south-north movement 

 of polar-alpine plants. To cite one case : Saxifraga flagellaris may be 

 considered to be a true arctic type which originated in the polar regions. 

 It is widely distributed on the Arctic coast of America, including 

 Greenland. It is known from Spitsbergen and Novaya Zemlya and 

 from several stations on the Siberian coast. Farther south it is 

 known from the Rocky Mountains (Colorado), Caucasus, Altai and 

 Baikal mountains, and the Himalayas. It is one of the most interest- 

 ing species of the genus. This arctic plant is of low stature, the flower- 

 bearing stem reaching a height of only i^ to 3 centimeters. The 

 shoot bears a number of fleshy leaves, glandular-hairy along the 

 margin, and the leaves form a small rosette. A single flower-bearing 

 stem with a few leaves and one or two flowers terminates the shoot. 

 Long runners are developed on the surface of the ground, consisting 

 of a single internode about 10 centimeters long terminated by a small 

 spherical rosette of green leaves. The main shoot dies off when the 

 fruit matures, and at this time the rosettes on the runners have 

 begun to develop roots and later give rise to independent plants. 



The alpine plants from the Rocky Mountains have taller, more 

 leafy flowering stems, and two to three flowers may be developed. 

 The plants are more glandular-hairy. In specimens from James Peak 

 (13,000 feet) the flower-bearing stem reached a height of about 15 

 centimeters, bearing seven flowers in a unilateral cyme. The flower- 



29 Cited in footnote 14, above. 



