Section IV, 1919 1671 Trans. R.S.C. 



Two plant associations from areas near Radville, Saskatchewan 



By Carrie M. Derick, M.A. 



Presented by D. B. Bowling, B.Sc, F. R.S.C. 



(Read May Meeting, 1919.) 



In the summer of 1918 Mr. John StansfieId,of the Department of 

 Geology, McGill University, Montreal, was engaged in making a soil 

 survey of part of southern Saskatchewan. Two collections of 

 plants made by him near Radville, Saskatchewan, in August, were 

 submitted to the writer for determination and description. The one 

 was obtained from a characteristic area covered with sandy soil, 

 approximately four inches in depth, overlaying a "peculiar sticky 

 clay." The other was collected on one of the so-called "burn-outs" 

 or shallow depressions, which often sharply break the general surface 

 of the country. From these spots, about four inches lower than the 

 higher levels, the sand has been completely eroded exposing the clayey, 

 sub-soil. Here, in the spring and after heavy rains, water stands long, 

 although the adjacent sandy places are dry. 



As is usual, the water relations are associated with marked 

 differences in the plant life of the two types of land; and these differ- 

 ences themselves vary from year to year, in accordance with variations 

 in the rainfall. Generally, however, the depressions are but scantily 

 clad with vegetation and growth is greatly retarded. Thus, in 

 the collections under consideration, many plants from higher levels 

 had already gone to seed, while the same species from lower areas had 

 only begun to bloom. 



Both of these conditions are doubtless due to the injurious effects 

 of water upon the seeds of land plants. As ShulP^ has shown, the 

 long-continued flooding of land practically eliminates all but hydro- 

 phytic and ruderal species. So, too, Crocker and Davis'' observed that, 

 "The seeds of water-plants in general are capable of lying in water 

 for years in the imbibed condition without losing their vitality. In 

 contrast to this, seeds of land plants will stand such storage for a 

 relatively short time." Probably the amount of oxygen necessary 

 to each species for germination is the factor which determines death 

 or survival, but the leaching out by the water of substances stored in 

 the seed may sometimes play a part. It is easy to say that favourable 

 conditions as to water, heat and oxygen are required for a viable 

 seed to germinate. But, as Clements^ has pointed out, with the 



