WATER REQUIREMENT AND ADAPTATION IN EQUISETUM 31 



(2) Wilting coefficient 



(a) Separate cultures. Equisetum fluviatile and Ranunculus 

 scekratus were grown in loam with a water content from 35-45% 

 maintained by keeping the pots in deep saucers filled with 

 water. The wilting point was determined by the wax seal 

 method. At the time of sealing, the Equisetum had grown six 

 weeks and the Ranunculus two months under the conditions 



TABLE 3 



Soil-water content at time of wilting, in Equisetum, Ranunculus and Helianlhus 



Equisetum fluviatile 



Plant (1) 23. T 



Plant (2) 24.4 



Plant (3) 23.0 



Plant (4) 30.0. 



Average 25 . 1 



Ranunculus sceleratus 



Plant (1) 13.5 



Plant (2) 11.0 



Plant (3) 14.1 



Plant (4) 14.7J 



Average 13.3 



Equisetum hyemale 



Plant (1) 5.3 



Plant (2) 5.3 



Plant (3) 4.2 



Plant (4) 4.7 



Average 4.9 



Helianthus annuus 



Plant (1) 5.8 



Plant (2) 5.4 



Average 5.6 



. Loam 



Loam 



.Sandy loam 



Sandy loam 



mentioned. A series of Equisetum hyemale growing in sandy 

 loam was also sealed for wilting. Because of the differences in 

 the soil the latter were checked against the wilting of two sun- 

 flowers also growing in sandy loam. The results are shown in 

 table 3. 



In order to check the soil water requirements of Equisetum 

 against those of typical mesophytes the following series of 

 experiments were undertaken. 



