439 



stomata are almost absent from the upper surface, but occur 

 very numerously upon the lower surface. Thalictrum alp. grows 

 in very dififerent localities. The fact that the leaves pass the 

 winter in a green condition may perhaps account for Coptis 

 trifolia being xerophytic. 



As a peculiar feature common to all the species may be 

 mentioned the fact that the epidermis contains chlorophyll. 

 As is well-known this is the case in temperate regions in plants 

 growing in scanty light, for example, in many aquatic and 

 woodland plants ; which appears to suggest that the species in 

 question have not been exposed to intense light— at any rate 

 not constantly. For further particulars the reader is referred 

 to LiDFORss ^ who states that a great many North-European ever- 

 greens have chlorophyll in the epidermis, especially that of the 

 lower surface of the leaf; the epidermis there is often separated 

 from the mesophyll by means of large lacunae and it will then, 

 on account of the presence of the chlorophyll, be more inde- 

 pendent in regard to its nutrition-physiology. 



Of the 14 species which have been investigated the stomata, 

 in the majority, were most numerous upon the lower surface, 

 viz. in R. affinis, acer, sulphureus, nivalis, pi/gmœus, lapponicus, 

 Anemone Richardsoni, Thalictrum alp. and Coptis trifolia, nine 

 in all. Of these Ran. lapponicus, Thalictrum aJpinum and 

 Coptis trifolia, have probably none, as a rule, upon the upper 

 surface. R. Pallasii has an almost equal number upon both 

 surfaces, a fact which perhaps is connected with the position 

 of its leaf, the lamina continuing the direction of the stalk. 

 The following species have the greater number upon the upper 

 surface : R. glacialis, hyperboreus (its leaves are sometimes 

 floating-leaves), R. reptans and perhaps Batrachium confervoides, 

 the last two in their aerial leaves. Borgesen (1. с.) states that 



' "Die wintergrüne Flora." Lunds Universitets Årsskrift, N. F. Bd. 2, 

 Afd. 2, No. 13. 1907. 



