SUNDEW 41 



dependent on what they obtain from the host plants to which 

 they become attached. Complete parasites, such as the Dodder 

 or the Broom-Rapes (which grow on the roots of a number of 

 different host plants) , are more profoundly altered in relation to 

 their mode of life than are the partial parasites. 



THE SUNDEW (Drosera rotundifolia, L.) AND THE BUTTER- 

 WORT (Pinguicula vulgar is, L.) 



The two plants just described were chosen because they 

 illustrated some of the modifications and adaptations found in 

 plants which live as parasites upon others, that is, take up the 

 more or less complex food substances they require from the living 

 host plant. Another interesting and well-known biological group 

 of plants is formed by those which obtain part of their food from 

 the complex substances forming the bodies of insects and other 

 small animals. These are known as insectivorous plants, and two 

 of the commonest to be met with on any moor or heath, especially 

 in mountainous regions, are the Sundew and the Butterwort. (See 

 frontispiece to Vol. III.) 



The Round-leaved Sundew (Drosera rotundifolia}, which is 

 represented in the accompanying plate, is the commonest British 

 species of the genus, but any of the others will do equally well 

 for study. It grows rooted in the peaty soil or very commonly 

 in a clump of Bog-Moss. To properly study the plant, patches of 

 the moss in which the Sundew is growing should be brought home, 

 placed in a soup plate with water, and covered with an inverted 

 tumbler or a bell-jar. They can thus be grown for a time and 

 experiments made upon them. 



The Sundew is a perennial plant, persisting over the winter in the 

 form of a resting bud. A well-grown plant bearing inflorescences 

 such as can be found throughout the summer is best examined 

 in the first instance, but the attempt should be made to follow 

 the history of the development during the year. Such a plant 

 consists of a short stem bearing a rosette of foliage-leaves, and 

 connected to the soil by a few thin sparingly branched roots ; 

 most of the roots are dark coloured, and have ceased to be of use, 

 while one is usually lighter in colour and functional. The foliage- 

 leaves are of peculiar shape, and construction and every detail 



