42 



The Plant World. 



find the Cypress scarcely if at all distinguishable from the still- 

 existing species as perhaps the most common denizen of the 

 shores of the greatly extended Plaisancien sea \\hich spread over 

 southern Europe and eastward into Asia. The'accomj anving 

 sketch map (Fig. 1) shows approximately the area over which 

 the Cypress became extended during the Tertiary period. 



Following the Tertiary came those climatic changes which 

 ushered in the glacial period of the Pleistocene. Our records 



Photograph by L. W . Stephemon 



Fig. 2. View showing the eroded upper surface of a Pleistocene Cypress swamp over- 

 lain by sand and gravel, near Waterview, Virginia. 



of Pleistocene migration are scanty, as might well be imagined, 

 but we krow that the' Cypress became extinct in Eurasia and 

 that it retreated toward the Gulf region in America, perhaps 

 oscillating southward and again northward'with'the'advance and 

 retreat of the ice front. We do have quite a large number of 

 American Pleistocene records of Cypress based upon the pre- 

 served trunks and typical knees like those shown in the figure. 

 The accompanying peat is often f acked with the cones and seeds 

 or perhaps a lens of clay may have preserved the deciduous 

 twigs. In one instance the writer collected unmistakable 

 staminate aments from the Pleistocene clays in North Carolina. 



