2710 The Romance of Wild Flowers 
pollen being detached by the stigma of the same 
flower, the stigma-lobe is pushed out of the way by 
the retreat of the insect. In P. lusitaniea self- 
fertilisation is effected by the stigma-lobe curling 
over into the anther-cells and thus getting pollinated. 
P. alpina is fertilised by flies; it has pale-yellow 
flowers with hairy throat, and it 1s no unusual thing 
for large species to get caught and to perish for 
want of the necessary strength to extricate them- 
selves. It would be interesting to learn by further 
observation whether this insectivorous plant has 
learned to make use of insects caught by its flowers 
as well as those captured by the leaves. 
The Bladderworts (Utricularia), of which also we 
have three native species, have yellow flowers similar 
in structure to those of the Butterworts, with the 
addition that the stigma is irritable, and its lobes 
fold up immediately they are touched—a precaution 
against fertilisation with pollen from the same flower. 
But the chief point of interest in the Bladderwort 
lies not in the flowers but in the bladders, from 
which it derives both popular and 
scientific names—utriculus being the 
: Ca Latin for bladder or bottle. The 
Ss |) plants grow in the waters of foul 
’ ditches and ponds, where there is an 
abundance of minute life. They are 
Bladderwort’s trap = quite destitute of roots, and float 
submerged a little below the surface 
of the water. Each leaf is reduced to a number of 
delicate threads, on the same principle that governs 
the submerged leaves of Water Crowfoot (Ranunculus 
aquatilis) and other aquatics. 
