384: E. W. Berry — Mid- Cretaceous Species of Torreya. 



a decided xerophytic habitat, but this does not accord with 

 the evidence of the associated flora, and the most reasonable 

 conclusion seems to be that this feature is rather to be corre- 

 lated with stem structure, i. e., to primitive water-conducting 

 tissues ; or as an inheritance from still older and more primitive 

 plants in which the vascular structure was still simpler. In 

 fact it seems quite probable that in dealing with modern 

 plants, one standard of values will have to be adopted for 



" c = SI fll | s a = « 



Part of ventral surface of leaf showing stomata, x 30. 



Angiosperms and another for Gymnosperms, since the latter 

 combine a usually marked xerophytic leaf-structure with 

 habitats not essentially xerophytic ; or as recently suggested 

 by Moss," comparisons between mesophytic deciduous vegeta- 

 tion or herbaceous plants dying down in the Fall, which 

 amounts to the same thing, and evergreen Gymnosperms, 

 should be on a basis covering the whole year, when it will be 

 seen that the latter are not xerophytes in the proper sense of 

 the term. When the present distribution of the species of 

 Tumion is considered, f it must be evident that the genus is not 

 strictly a member of the existing flora, but a relic of a prehis- 

 toric one in which it was a far more abundant and widespread 

 element, and it seems quite probable that many centuries will 

 not elapse before it becomes entirely absent in the living flora. 

 The almost extinct T. taxifolium making its last stand on the 

 narrow ridges that extend out into the Apalachicola river 

 swamps, separated by over 3000 miles from T. calif ornicum 

 of the mountains of California,^: and this in turn separated by 

 the breadth of the Pacific from the two species restricted to 

 the mountains of China and Japan, § all point to the same 

 conclusion. When we turn to the geological record we find 

 it so meager and incomplete that it does not, as yet, possess 



*New Phytologist, vol. vi, pp. 183-185, 1907. 



f This peculiar distribution was dwelt upon by Prof. Asa Gray in his 

 presidential address before the American Association for the Advancement 

 of Science at Dubuque. Iowa, in 1872. 



% Mendocino county to the Santa Cruz mountains along the Coast Eange 

 and somewhat more abundantly at middle altitudes on the western slopes of 

 the Sierra Nevadas. 



§ T. nucifera of the mountains of Nippon and Sikok and T. grandis of the 

 mountains of northern China. 



