40 MADRONO [Vol. 1, 



mate and alpine climate, namely, the temperature of the air at the 

 time of the melting of snow. This temperature increases with the 

 altitude. Hence it comes that the alpine flora finds a warm air im- 

 mediately after the melting of snow. So we understand the fact that 

 close to the edges of snow-fields we find the bright colors of alpine 

 spring flowers. 



Very important for the growth of alpine plants is the fact that 

 the alpine vegetation begins late in the year, in June or July, when 

 the days are long and the nights are short. Now, you know that it 

 is especially in warm nights that plants grow and shoot their stems, 

 whereas the light of the day favors the production of organic ma- 

 terial by means of the energy of the sun-rays. Thus our alpine 

 plants are able to assimilate copiously during the long warm days 

 with their strong insulation ; but in the short and often very cool 

 nights they cannot prolongate their stems; hence the dwarf habit 

 of alpine plants ; it is a direct effect of climatic favors. 



But we must be aware of the fact that there exists another 

 dwarfness, a hereditary one, not directly produced by alpine fac- 

 tors, but favored by natural selection. The dwarf Pine (Krumholz, 

 Pinns montana Mill. var. prostrata Tubeuf), for instance, remains 

 dwarf even in the lowlands ! It is clear that a dwarf habit is very 

 useful to alpine plants in many respects: against the mechanical 

 effects of the thick layer of snow ; as a means of protecting the plant 

 against frost and the winter dryness, being covered by snow ; and as 

 a means to take advantage of the warmth of the soil. 



The mountains are well known as rain and snow catchers; the 

 layer of snow is thick and lasts a long time. How enormous quan- 

 tities of snow may accumulate at places is shown in a picture taken 

 by Dr. Riibel at the Berninapass, where the stage is driving between 

 snow walls 9 to 12 feet high. 



III. 



But enough of this preparation : let us now enter the living alpine 

 world and become acquainted with its principal types. We begin 

 with the alpine thicket and its most popular shrub, the Alpenrose, 

 the queen of the alpine flora, which garbs in radiant purple entire 

 slopes. We have two kinds of Rhododendron in our Alps ; the two 

 are evergreen shrubs with leathery leaves. The brown one (Rhodo- 

 dendron ferruginum L.) has leaves which are brown underneath 

 through glandular scales; the hairy one (Rh. hirsutum L.) has very 

 few brown scales, and the edges of its leaves are fringed with long 

 hairs. If the two grow side by side, regularly there arises a natural 

 hybrid: if a busy bee transposes some pollen from stamina of a 

 hairy specimen to stigma of a brown one, there ripens a seed out of 

 which grows an intermediate being which shows a mixture of the 

 characters of both parents. Our alpine roses are old Tertiary pure 



