224 THE STORY OF PLANT LIFE 



facilitating this. Another adaptation in the leaf is 

 that the chlorophyll granules arrange themselves in 

 position according to the intensity of the illumina- 

 tion. 



Worm Grass, Prick Madam, Great Stonecrop, are 

 the other names. 



The Stonecrop or House-leek used to be named 

 Thunder-beard, and if the latter was planted on a 

 house roof it served as a talisman against lightning. 



Sedum album. — The barren shoots of flowering 

 stems with the creeping rhizome and rootlets are shown 

 in Fig. 45, with the terminal corymb, and the flowers 

 show the sepals and petals, stamens and ovary. 



29. The Sundew Group. 



In Britain we have three representatives of the 

 order Droseracese or Sundews. There are some 

 other foreign types which are also, like our own 

 plants, insectivorous. These include Dioncea and 

 Aldrovanda, in which the leaves are sensitive and 

 close up when touched. In the other genera Droso- 

 phyllum, Dvoseva, Byblis, Rovidula, the plant catches 

 its prey, consisting of insects, by aid of sticky 

 tentacles which cover the upper surface of the 

 leaves. 



There are about a hundred species of this order, 

 members of the foregoing six genera. The Sundews 

 proper include a large number of species, which are 

 found in all parts of the world, especially Temperate 



