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are bushes of Tamarix and Salix angustifolia with narrow- 
leaved Populus euphratica, while masses of Glycyrrhiza glabra 
hide the ground. The dominant plant after the poplars is 
Apocynum venetum, which attains the height of 2—3 metres 
and has thin stems, the growth being that of a semi-liane 
supporting itself on other bushes by the aid of its out- 
spreading branches. These extend horizontally and through 
their own weight become pendulous, the extremities bearing 
inflorescences of handsome red blossoms.) When Apocynum 
venetum grows on treeless ground, the branches lie prostrate 
along the surface. 
Also Clematis orientalis and Cuscuta Lehmanniana I have 
recorded as being of frequent occurrence in thickets of the 
above type. 
The thickets described above must be regarded as true 
riverside or gallery forest, an edaphic formation whose differ- 
entiation from the surrounding formations depends solely 
upon the presence of the river; in the first place the thickets 
are only found along the river, and secondly one can see 
that further from the river they become thinner and lower. 
Such is for instance the case at Kogertlé on the right bank 
of the Amu Darya. Here the river-bed is much wider than 
the river and is evidently subject to periodical flooding. 
The plain is covered with thick luxuriant forests of poplars 
interspersed with Phragmiteta and glades with Erianthus and 
Tamarisk. Gradually as one goes farther away from the 
river, the forest thins out and the poplars become lower 
and less vigorous. The clumps of trees become separated 
more and more by open spaces occupied only by isolated 
plants of Glycyrrhiza glabra, Halimodendron argenteum, Zygo- 
phyllum Eichwaldi, Tamarix or low poplar-bushes. The 
Tamarisks become more frequent until as almost pure com- 
munities they form the outposts against the brown bare hills 
of the desert. As will be shown later (chap. 11), the Tama- 
risks may even invade the desert, where by means of their 
very long roots they can always secure water from deeper 
layers. 
1) A fibre obtained from Apocynum venetum is used by the natives 
for cordage under the name “red hemp” (Kisil Kandir). 
