ALPINE PLANTS IN THEIR NATIVE HAUNTS. 



71 



Androsaces abound in the Alps at high altitudes. Moreover, we 

 find that many plants which grow in the lowlands have their closely 

 allied alpine forms differing from them in scarcely any respect except- 

 mg habit of growth. Myosotis alpestris is practically identical with 

 Mijosotis sylvatica; the common juniper which grows in this country 

 has its dwarf form in the Alps growing scarcely higher than the ordinary 

 ling. The willow is in the Alps represented by the creeping shrubs, 

 Salix Jierbacea and S. reticulata, the Silenes by several dwarf forms, 

 of which Silene acaulis is particularly remarkable for its close cushion- 

 like habit. Apart from these there are several genera of plants, such 

 as the Androsaces, which are almost exclusively alpine, represented by 

 several species, all of which are exceedingly dwarf in habit. 



Many and various are the theories which have been advanced to 

 explain this habit of growth in alpine plants. It has been argued that 

 it is an adaptation to the violence of the alpine storm, and to the pres- 

 sure of the weight of snow which the plants have to bear in winter. 

 The effect of the wind upon vegetation can be observed in our own 

 country by the sea coast, and it would probably be going too far to say 

 that the fury of the alpine storm has no effect in contributing to the 

 dwarf habit of alpine plants.^ It may well have helped, for instance, 

 to make the more erect form of Juniperus communis, which we see in 

 this country, impossible for alpine regions, so that we have instead Juni- 

 perus communis nana as the alpine form. In the same way, the weight 

 of snow may have contributed to a limited degree to the dwarfing of 

 the shrubby plants of the high Alps by breaking down the taller speci- 

 mens, and thus establishing a selective process in favour of a dwarfer 

 habit, f Keener, however, emphatically declares that the clinging of 

 woody plants to the ground in high alpine regions must not be regarded 

 either as an adaptation to snow pressure or to storms. "It is," he 

 says, "due rather to the fact that in the high Alps the ground is rela- 

 tively much warmer than the air, and that plants lying on the soil profit 

 by this higher temperature." I To this again it may be answered that 

 many of these creeping woody plants, such as Salix reticulata and Dryas 

 octopetala, are also indigenous in Arctic regions, where these conditions 

 as to temperature of soil and atmosphere do not obtain. While I do not 

 wish to suggest that these theories should be entirely disregarded as 

 explanations of some of the causes contributing to the dwarf habit of 

 alpine vegetation, I cannot help feeling that the evidence points to the 

 accuracy of the view that it is to the intensity and quality of the alpine 



i light, and to the climatic conditions, that we must look for our 

 explanation of this problem, rather than to the mechanical action of 

 btorm and snow pressure, or to the advantage which procumbent plants 

 may derive from relatively higher soil temperature. 

 Even the most casual observer of the habit of plants cannot fail to 

 notice the very marked effect which the intensity of the illumination 

 [ * Schroeter, op. cit. p. 664. 



I t Schroeter, op. cit. p. 663. 



I + Kerner, op. cit. vol. i. p. 525. Schroeter, op. cit. p. 647. 



