FLOWER AND FRUIT D Wess 
the pollen is ready for use. The different stages in the 
opening of this flower are most peculiar, but, so far 
as ean be learned, have no direct bearing on its pollin- 
ation. First the perianth tube opens at the tip to 
expose the apex of the style, where the stigma, lying 
in a small depression, is not yet ready to receive the 
pollen. Next, longitudinal splits appear near the base 
of the tube, and finally the whole perianth splits into 
four segments which curl back. Thus the inflorescence, 
which bears a considerable number of flowers, forms, 
when mature, a tangled mass of perianth lobes. The 
tuis, thrusting their tongues among the now exposed 
styles, get the pollen dusted on their heads, and may 
earry it to other flowers in which the stigma has 
arrived at the receptive stage. In this way cross- 
pollination is effected. 
Water is, in some rare instances, the agent of pollin- 
ation. This is the case with vallisneria (Fig. 110), the 
male plant of which is so plentiful in Lake Takapuna, 
where, beginning as a tiny shoot, it has vegetatively 
reproduced till it is a serious impediment to the use 
of boats upon the lake. The plant is diccious. The 
stem having the pistillate flower rises to the surface 
where the flower opens and displays its stigmas. The 
staminate flower, however, is produced below the water 
at the end of a short stalk. Before the buds expand 
they break off and rise to the surface, where they 
open and expose their stamens. These, floating on the 
surface, may come into contact with pistillate flowers 
and thus bring about eross-pollination, which, of course, 
seeing that the plant is diccious, is the only kind 
possible. 
INFLORESCENCES. 
Mention has been made of the advantage for insect 
attraction possessed by a showy flower. Where such 
flowers are collected in groups, this advantage is 
