— 120 — 
by plants which I saw in the Turkestan herbarium in the 
Imperial Botanical Gardens at St. Petersburg; according to the 
labels they were all collected on the Amu Darya near Chiwa. 
Najas major Roth., N. minor All., Ruppia maritima, L., 
Zanichellia pedicellata Fr., Butomus umbellatus L., Vallisneria 
spiralis L., Salvinia natans Hoffm. 
The following species which 1 collected in various small 
Chiwensian lakes may perhaps be of interest in this con- 
nection. 
In salt-lakes where Salicornia not only fringed the border 
but also entered the water: Phragmites (withered), Scirpus 
affinis, Ruppia maritima, (Comp. above p. 55). 
In fresh or slightly saline lakes, Phragmites is often 
dominant; the growth is here very dense and strong, and 
single reeds may attain a height of more than 4 metres. 
In other small lakes, Typha angustifolia and T. latifolia 
are dominant, interspersed with Scirpus littoralis or Calamagros- 
tis pseudophragmites, and in lakes of this kind the following 
submerged plants were found: Potamogeton crispus and fluitans, 
Myriophyllum, Ceratophyllum demersum, and Polygonum am- 
phibium with floating leaves. 
CHAPTER 11 
Descriptions of Vegetation from selected Localities. 
In the previous description of the various desert-forma- 
tions, the distinction between them is based mainly on the 
soil in which the plants grow, but it has also been attempt- 
ed to characterize them by means of their growth-forms. 
Taken as a whole it seems to be the case that a different 
soil produces different growth-forms. One thus refers to the 
switch-trees and the dry and thorny herbs of the Sand-desert, 
to the dwarf-bushes and halophytes of the Clay-desert, and 
to the richly leaved trees and lianes of the Riverside Thickets. 
