RP TA es 
the same structure. The leaves are isolateral, with 2—3 
layers of palisade-cells on each side and a thin spongy 
parenchyma in the centre. In some cases there is a band of 
sclerenchyma over the nerves, but this is by no means always 
the case. The epidermis has never more than a single layer, 
is not thick, nor thick walled; there are always stomata 
on both leaf-surfaces, they are on a level with the epidermis 
except in the Oxytropis-species, where they are depressed to the 
inner line of the epidermis. Oxytropis tibelica has epidermis 
cells filled with mucus. 
The following species have a deviating structure: 
Sisymbrium Korolkowits leaves are dorsiventral with 4 
palisade-layers on the upper surface, loose spongy tissue, thin 
epidermis with stomata on both sides. 
Trigonella Emodi has likewise a dorsiventral leaf, yet 
with palisades on both surfaces. The mesophyllum is loose 
on the whole; the cells of the epidermis are papillose-curved, 
very thin walled, and filled with mucus; there are bi-cellular 
glands and slightly depressed stomata on both sides. 
Finally, the winter-green species, Acantholimon alatavicum 
and diapensioides and Arenaria Meyeri have acicular or scaly 
leaves with many sclerenchyma-bands and 2—3 layers of 
palisade-cells the entire way round. The epidermis consists 
of one layer with a thick outer wall and slightly or non- 
depressed stomata. In Acantholimon diapensioides the cells of 
the epidermis are papillosely protuberant, in Arenaria they 
have thick walls all the way round. 
The leaf anatomy of the majority of the plants of Pamir 
agrees in the main points with that described by WAGNER 
and by Bonnier as typical for alpine plants. The great 
development of palisade-cells is especially striking, and one 
is apt to assume that the plants of Pamir, like the euro- 
pean alpine plants, are adapted to a powerful assimilation 
of carbonic acid (cf. BONNIER). In any case the majority of 
species of deciduous plants in the Pamirs seem to be in coin- 
cidence with their surroundings, when they have small, 
hairy, isolateral leaves with well-developed palisade 
tissue, thin epidermis and stomata on both sides. 
