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 AIL, 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: Phrag mites (withered), Scirpus 

 af finis, 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. 



