CHARACTERISTICS OF ALPINE PLANTS. 113 
tion. It consists in their case of a number of hairs, which 
retain a “‘ layer,’’ if we may employ that term, of air, which 
prevents rapid evaporation and undue strain upon the stomata 
or pores of the leaves. It is exceedingly interesting to 
observe how, even in cultivation, this feature becomes more 
developed when leaves are exposed to the sun. Some plants 
of these Saxifrages will show a small supply of hairs when 
in the shade, and a greatly increased number in sunny places. 
For shelter against the parching heat of strong sunshine 
it would hardly be expected that the Sempervivums, or 
Houseleeks, would require any such arrangement, but certain 
species are fully provided with hairs, in some cases only along 
the thin leaf-margins, but in others all over the leaves, and 
in a few species this is still further supplemented by a cob- 
web-like arrangement of hair stretched across the rosette in 
the most delightful way. 
This brings us to the fleshy or succulent nature of the 
leaves of many of these plants. This provides a store of 
moisture, on which the plants can draw during drought, and 
is very apparent among the Sempervivums and Sedums. It 
may be mentioned, however, that such arrangements as those 
remarked upon for protection against drought are not pecu- 
liar to Alpines, but are common among plants exposed to 
excessive drought at certain times. 
Another method of protection is that afforded by a floury 
“or mealy substance, which clothes the leaves—generally the 
lower surface—and frequently the stems and bracts of certain 
flowers. This serves in some measure as a screen against 
the strain on the plant caused by the refraction of the sun 
on the snow about the plants. I am not aware, however, if 
this question has been as fully considered as one might ex- 
‘pect, and I have a measure of doubt as to the reason of this 
powdery arrangement. 
A marked characteristic of the Alpine plants is the scale- 
like coverings which shield the stomata of certain subjects. 
Some plants, such as the Alpen Rose—Rhododendron ferru- 
gineum—have a brown, rust-like appearance underneath the 
leaves. This is composed of a series of scales covering the 
