7 6 



ZONES AND REGIONS [Pt. Ill, Sect. IV 



hispid foliage is characteristic of such scree-plants. They are all rooted 

 in cold wet soil that is irrigated by glacier-water. In spite of the 

 superfluity of moisture, the habitat is physiologically dry and causes the 

 differentiation of protective measures against rapid transpiration. Similar 

 but far more succulent foliage is possessed by Saxifraga aizoides, the 

 characteristic riparian plant of the alpine glacier-brooks. Such plants 

 strongly recall in their structure the halophytes of wet stations ; they 

 agree with them at all events in their physiological environment, in that 



they inhabit wet habitats and are nevertheless 

 exposed to danger from want of water. The 

 moist air surrounding them offers a hindrance to 

 the production of hairs and of a thick cuticle, 

 but is inoperative as regards that of coatings of 

 wax and resin as protective measures against 

 transpiration. 



Above the alpine grassland fields of perpetual 

 snow extend to the summits of the mountains. 

 There is no upper limit for the phanerogamic 

 flora of the Alps, such as we found to be the 

 case on Kilimanjaro, for even at the greatest 

 altitudes the air is not sufficiently dry or rarefied 

 to prevent their existence. In the fissures of rocks 

 that projected above the snow and ice on the 

 Kaltwasser Glacier of the Simplon, I found, in 

 August, numerous blossoming plants of Eritri- 

 chium nanum,Androsaceglacialis,AretiaVitaliana, 

 and Anemone glacialis. Martins collected in the 

 St. Theodule Pass, at an altitude of 3,333 meters, 

 thirteen phanerogams, which, according to Christ, 

 represent only a part of the flora. Lindt found 

 on the Finsteraarhorn, from 4,000 meters upwards, 

 Saxifraga bryoides, S. muscoides, and Achillea 

 atrata ; and Calberta found on the summit of the mountain, at 4, 2 7° meters, 

 an apparently annual specimen of Ranunculus glacialis with two somewhat 

 stunted flowers. 



Fig. 475. Primula minima. 

 Natural size. 



CONDITIONS OF TEMPERATURE IN THE ST. THEODULE PASS. 



(3,333 meters above sea-level.) 



1. Mean monthly temperature in Centigrade. 



