CXXVI.— THE MOUNTAIN AVENS. 
Dry as octopetala Linne. 
T he vivid greenness of their compact cushions of foliage, early in the year, 
and their many, and relatively large, gaily-coloured blossoms closely nestling 
among the leaves, have not unnaturally brought about a cult for alpine plants among 
garden-lovers. They are seen at their best when, in their natural surroundings, 
their roots or rhizomes holding fast in some hidden crevice through which trickles 
the melting snow, they cling to some steeply sloping surface of bare grey rock in 
what the ecologist terms an open community of chomophytes. In winter — for they are 
almost always perennial — they may be sufficiently protected from frost by the snow 
that drifts on to the rock-ledges : their habit of growth enables them to defy the 
fierce winds to which they are constantly exposed ; and they rejoice in the full glare of 
the sun, which they can utilise, when it is at its lowest altitudes, to unfold their 
blossoms and to ripen their fruit. The species that can endure these conditions are 
not numerous ; and the small modicum of soil which even they require will not 
apparently support many individuals. Their struggle for existence, in fact, is rather a 
struggle against physical disabilities than against competing plants ; and this is what is 
implied when these chomophytes, or screes-plants, are said to be in an open community. 
Their conspicuous flowers often produce more or less concealed honey, so as only to 
reward the visits of long-tongued insects, such as the butterflies, which frequent 
greater altitudes in the mountains than any other group of insects. There are, 
however, wind-pollinated Rushes among their associates, and Dwarf Willows that 
occupy a physiologically intermediate position. It is not because the situation of these 
alpine chomophytes is deficient in water-supply that their leaves exhibit xerophytic 
adaptations ; but rather, perhaps, that the low temperature of the soil-water largely 
inhibits the absorptive action of their roots. Transpiration has, therefore, to be 
lessened, and the leaves have accordingly a leathery texture with thick epidermis and 
hypodermis and with stomata, or transpiration-pores, sunk below the general level of 
their surface or protected by dense woolly hairs. A polished upper surface and a 
serrate margin are, perhaps, protections against the prolonged adhesion of the 
crystals of snow. 
Among British plants there is no more typical or more beautiful a representative 
of this alpine type than Dryas octopetala Linne. Though Petiver apparently applied 
the English name Mountain Avens to Geum rivale, it would seem to belong yet more 
appropriately to this species. 
The genus to which it belongs is a small one, consisting but of two or three 
species ; but well distinguished from Geum by its simple leaves, solitary flowers, the 
absence of an epicalyx, and the styles which have no articulation but grow out into 
long feathery awns, as in Clematis and Anemone Pulsatilla. This last character is one 
of the many interesting parallelisms between the Rosacece and the Ranunculacece. In 
