162 
and lower parts were on the verge of decay. The cork-layer 
on these old stems is always thin and smooth. 
The peculiar, ericoid leaves of Empetrum occur sometimes 
very closely together, as on the short, erect shoots, and some- 
times at a distance (as much as 0°5 cm.) from each other, as 
on the longer, creeping shoots. 
The leaves are functional for about three years, but may 
persist for a longer time in a decaying and shrivelled-up 
condition. When the Empetrum-tufts or mats, even at a great 
age, present an abundance of leaves, this is due to the excessive 
and dense branching which always occurs under favourable 
conditions as regards shelter, etc. But in habitats where it 
is exposed to the influence of a constant and strong wind it 
assumes a very different appearance. Korperup Rosenvince (11, 
p. 188) describes such wind-affected individuals from bleak 
heaths in South Greenland. He writes that old plants present 
“a green border which surrounds an inner part consisting 
only of the old, crooked branches.” “The green borders are 
not developed all round, but only one side, in the form of a 
somewhat irregular, almost semi-circular curve.’ All the curves 
turn away from the direction of the prevailing wind. See 
photograph from the Kitsigsut-islands (p. 189, Fig. 9). After- 
wards Rosenvince describes and figures such wind-affected tufts 
of Empetrum (see p. 255 and Fig. 11) the leaves of which are 
very considerably reduced in number, and in which the for- 
mation of adventitious shoots is undoubtedly impossible on 
account of the influence of the wind. 
The leaves on the shoot of the current year are obliquely 
erect; on the shoot of the preceding year they are more 
spreading and stand out somewhat at right-angles, and on 
still older shoots they are usually twisted somewhat backwards. 
They are orientated by the torsions of the extremely short 
stalks so that they turn their surfaces upwards towards the light. 
Hacionp (6, p. 31) mentions, that the leaves are consider- 
