DROSEEACE.^ 



201 



DEOSEEACEJ^: 



Drosera (Sundew) 



We have three species, which, however, do not seem 

 very well marked off from one another. The Common 

 Sundew [D. rotundifolia, Fig. 138) has the ends of 

 the leaves obovate or orbicular, as broad as long. In 

 D. anglica (Fig. 139) they are linear-spathulate, five or 

 more times longer than broad ; but in D. longifolia the 

 leaves are almost intermediate in form. D. rotundi- 

 folia and D. anglica produce cleistogamous flowers. 



In the species hitherto described the relation between 

 the flowers and insects is one of mutual advantage. 

 The honey of the flowers affords 

 to the insects a rich and nutri- 

 tious food ; and if the latter rob 

 the flowers of some of their pollen, 

 they make ample amends by carry- 

 ing a portion of the remainder 

 from one flower to another, and 

 thus conferring on the plant the 

 great advantage of cross-fertilisa- 

 tion. In Drosera on the contrary, 

 we find a very different state 

 of things, for the plant catches 

 and devours insects. This genus, 

 and the other plants which have 

 this remarkable habit, were the Fig. 138.— Drosera wtundi- 

 subject of an admirable memoir & anlrpl'tTi'^"'"'^' '"*^ 

 by Sir Joseph Hooker, read before 

 the British Association,^ of a special work by Darwin, 

 aiid of many subsequent observations. The first observa- 

 tion of insect-eating plants was made about the year 

 1768 by our countryman Ellis, on Dionsea, a North 

 American plant, the leaves of which have a joint in 

 the middle, and close over, kill, and digest any insect 

 which may alight on them. The plant has more 



' Nature, September 3, 1874. 



