18 SOME BRITISH PLANT GROUPS 
it grows, flourishing equally upon a number of hosts, 
and even capable of living upon its own species. It 
differs from those parasites which we have been con- 
sidering in possessing an abundance of green leaves, 
and being therefore capable of manufacturing its own 
food. At the same time, it has no roots which can 
penetrate the soil, and is incapable of an independent 
existence. It seems probable that its relations with its 
host are to some extent symbiotic—that is, each giving 
to the other—rather than purely parasitic, where the 
benefit is entirely on one side. The Mistletoe, retain- 
ing its leaves and manufacturing food throughout the 
year, is clearly capable of aiding its host, which loses 
its leaves in autumn, and cannot form fresh nourish- 
ment until spring is well advanced. 
Before leaving this question of abnormal methods 
of procuring food as found among the higher plants, 
we may return for a few moments to the consideration 
of carnivorous plants, to which reference was made in 
Chapter IV. Of these the Sundews (Drosera), Butter- 
worts (Pinguicula), and Bladderworts (Utricularia) 
supply very interesting examples within our own flora, 
which anyone may study on a holiday spent on the 
moors or mountains. The Sundews are familiar to all 
plant lovers—little plants of the bogland, usually 
growing among Sphagnum, and well distinguished by 
their leaves decked with spreading red hairs, each of 
which is tipped with a little drop of sparkling sticky 
fluid. It is these hairs or tentacles and their move- 
ments which place the Sundews among the most 
interesting of all plants. It is important to note that 
they are not hairs in the ordinary sense, which are 
organs of very simple structure arising from the 
