ARCTIC PLANTS 
181 
the soil is thin, and liable to be very much heated at the 
surface whilst it remains very cold at a little depth (thus 
hindering absorption by the roots) ; insects are few and far 
between, and belong chiefly to the lower classes, especially 
the Diptera. It is evident therefore that xerophytic structure 
is a necessity, and in fact it is very marked in the arctic flora. 
The long-continued light retards growth and the plants show 
a dwarfed and tufted habit, as may be seen in the common 
genera Diapensia, Draba, Loiseleuria, Vaccinium, Saxifraga, 
&c, They also exhibit many of the xerophytic characters 
described above — reduced surface, closely-packed leaves, 
inrolled leaves, fleshiness, thick cuticle, hairiness, sunk 
stomata, and so on. The flowers show, as compared with 
the same species in warmer regions, an increased tendency 
to autogamy, and there is a marked increase of vegetative 
propagation, especially in species that are not capable of 
autogamy. Eutropous flowers are few, and often have 
shorter tubes, which enable hemitropous insects to reach 
the honey (p. 94). The genera above mentioned grow 
chiefly in the more rocky or dry places ; the wetter moors 
are occupied by such plants as juncus, Scirpus, Carex, and 
many grasses. Most of these are characterised by erect 
centric stems or leaves, so that the green tissue is almost 
or quite symmetrically arranged, facing to every quarter of the 
compass. Jungner regards this as an adaptation to the pecu- 
liar ‘ circumpolar ’ light that falls on every side of the plant 
in turn. Annual plants are comparatively few in number, and 
few woody species occur • the arctic species of Betula, 
Salix, &c. are low-growing, almost herbaceous plants. 
The resemblance of the flora of the Grampians or the 
mountains of Norway or Germany to that of the arctic 
regions is at once evident, most of the species being the 
same. At low levels the flora is like that of the lowlands 
from which the mountains rise, but marked by the absence 
of many species and the presence of others (subalpine), 
e.g. Meum, Viola lutea , &c. In ascending, the lowland 
species gradually disappear ; very few of them reach above 
1000 feet in the Grampians, and these mostly do not pass 
above 3000 feet, while other species take th£ir place and in 
turn disappear at still higher levels. The upper limit of 
trees (Coniferae and Betula) lies at about 2000 feet in the 
