40 THE FLORA OF THE ALPS 



Sundews are remarkable for their insectivorous habit, 

 insects being detained by the viscid excretion from the 

 stalked glands which cover the margin and upper surface 

 of the leaf, and then digested in a chamber formed by the 

 infolding of the leaf. 



The three British species, D. rotundifolia, L. ; inter- 

 media, Hay. ; and the larger and less common, D. anglica, 

 Huds. {longifolia, L.) ; are found in similar situations 

 throughout the region, in Sphagnum bogs and by moun- 

 tain streams. 



2. Aldrovanda, L. 



Flowers solitary, axillary ; petals 5 ; sepals 5 ; leaves 

 in whorls. Aquatic. 



A. vesiculosa, L. ; the whorls of 6-9 very thin sub- 

 merged leaves bear bladders, in which small aquatic 

 animals are captured and digested ; a Southern plant ; 

 Lake of Constance, Tirol, Pyrenees. 



Order XH.— CARYOPHYLLE^E. 



Flowers regular ; inflorescence always cymose ; sepals 

 and petals usually 5 each; stamens usually 10, in two 

 rows; ovary i -celled with central placentation, or par- 

 tially 2-5 -celled with axile placentation ; leaves always 

 opposite and entire, springing from swollen joints. A 

 large order, almost confined to the arctic and temperate 

 zones of the Old World. 



Tribe SiLENE^. — Sepals 4-5, more or less united at 

 the base; styles 2-5, free; disk elongated, bearing the 

 petals and stamens. Genera 1-8. 



