416 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Alpine Plants. 



Tourists in Switzerland cannot fail to notice that high Alpine plants 

 are dwarf in size, but have very brightly coloured flowers, such as those 

 of the deep blue of some Gentians and the red blossoms of Saxifraga 

 oppositifolia. 



These and other features, as well as the correlated anatomical 

 structure of the leaves, &c, are simply the outcome of the surrounding 

 conditions. This has been proved experimentally. Moreover, there are 

 innumerable coincidences between all the floras of high mountains. 



The external conditions, which are very similar to those of Arctic and 

 Antarctic regions, are the relative amount of continuous light through 

 the summer months, coupled with a diminution of heat and moisture 

 with a cold subsoil relatively poor in nitrifying microbes. These render 

 the plants more or less xerophytic. 



The prostrate habit of many is due to the responsiveness of the plant 

 to the higher temperature of the surface of the ground when warmed by 

 the sun compared with that of the air above the surface. The brighter 

 colours of the flowers are due to the enhanced assimilative powers of the 

 leaves, in response to the prolonged amount of sunlight during the 

 growing period. 



So that, both by inductive evidence and experimental proofs, the 

 ecology of Alpine plants is thoroughly accounted for. 



Arctic Regions. 



The most obvious feature is the stunted growth. Plants attaining a 

 few feet in Scandinavia only grow to a few inches in the highest latitudes. 

 The character of the plant- organs is thoroughly xerophytic and closely 

 resembles those of hot southern deserts. 



The low temperature, cold soil, and continuous illumination are the 

 chief factors of the environment to which all plant-structures correspond. 

 It is remarkable that there is no special protection against excessive cold, 

 the protoplasm itself having acquired an immunity. 



The reproductive processes are remarkable for abundance and brilliancy 

 of the corollas from the continuous illumination for so many months. 

 But, though the light be prolonged, there is often a deficiency of ripened 

 fruits. 



Unlike what occurs in hot deserts, ethereal oils are rare as well as 

 scented flowers and aromatic vegetative organs. 



Tundra. 



The last distinct plant-formation is the Arctic Tundras. These are 

 called Moss-, Lichen-, or Rock-Tundra, according to the prevailing kind 

 of plant in the first two, while the third shows an absence of plants. 

 Shallow, moist depressions, with sphagnum, &c, constitute Arctic moors, 

 while sunny slopes abound with flowering plants, resembling garden 

 flower-beds, and are called " Heat-oases." 



