WATER RELATIONS OF SOME PSAMMOPHYTES 

 WITH RESPECT TO THEIR DISTRIBUTION 



MiLENA Rychnovska & Jan Kv£t 



Geobotanical Laboratory of The Czechoslovak Academy of Sciences 



Brno, Czechoslovakia 



INTRODUCTION 



The psammophytes in Czechoslovakia are grouped in characteristic plant 

 communities on sandy soil. Although various plants in these communities 

 require the same substratum, they belong to widely different areas of 

 distribution. A small strip of land having uniform edaphic and climatic 

 conditions may thus contain both continental and oceanic species, in 

 addition to those commonly found in the Northern Hemisphere (i.e. 

 holarctic plants). For some species Czechoslovakia forms part of the 

 boundary of their areas of distribution. The sandy region of Southern 

 Moravia was thus a highly suitable place for the physiological analysis of 

 some characteristic plants. Such analysis could lead to the causal explanation 

 of their distribution in Central Europe. Water relations of the psammo- 

 phytes and their habitats, besides their common specific adaptation to 

 sandy soils, were considered, after numerous observations, comparisons and 

 experiments, to be an important factor in the distribution of these plants 

 in Czechoslovakia. Having all these facts in mind, we performed a field 

 experiment in which we measured the daily variations in transpiration of 

 three characteristic psammophytes. A group of plants was artificially 

 supphed with water and a control group was observed under natural 

 conditions. 



METHODS AND MATERIALS 



During three characteristic days in the middle of the growing season 

 (1-3 June, i960) we observed the transpiration of the following plants: 



Corynephorus canescens (L.) P. Beauv. 



Festuca dominii Kraj. {Festuca ovina subsp. euovina var. vaginata Hack. 



p. p.) 

 Helichrysum arenarium Moench. 



They were growing on sand dunes near the railway station of Straznice- 

 Privoz in Southern Moravia. The tufts selected for experiment were 

 approximately of the same age. Some of them were artificially supplied 



