136 TYPES OF BRITISH PLANTS 
course no one can say for certain, but it is suggested that 
the Butcher’s Broom is especially anxious for moisture, 
which it cannot get in sufficient quantity on its favourite 
waste-ground habitats, and that the stems do not allow 
of so much evaporation as leaves would. Others say 
that it may be due to a desire to drive away browsing 
animals, and any one of these theories is possible, but 
none of them is proved. 
The Iris flower deserves a close examination, for it can 
boast of an ingenious con- 
trivance to ensure. the ser- 
vices of bees, as well as the 
beauty of colour and shape 
that we noticed before. 
Looking at the illustration, 
which is of the large garden 
Iris, you will notice the two 
threes, the falling sepals and 
the erect petals. Towards 
the base of each sepal is a 
furry patch, which guides 
the welcome bee to the 
honey. Arching over the 
three sepals we see the three 
parts of a most elaborate 
stigma (pistil-top), beneath 
which are sheltered the 
: three stamens. As the bee 
ee ee forces its way down, the 
pollen it has brought, or some part of it, is scraped off 
by the edge of the pistil’s lip and from the anthers. If 
they are ripe it gets a fresh supply. The relative position 
of the pistil and stamens makes it almost certain that 
AN 
