172 Botany

are some of the means by which visits of unsuitable
insects are prevented: -

1. Isolation - The bladderwort (Utricularia) flower
floats on the surface of the water, so that none but
flying insects can reach it.

2. Sticky juices, secreted at each node of the stem
in certain species of catchfly, prevent creeping insects
from reaching the flower

3. Hairs in the salvia, act as a barrier to insects
that would not be strong enough to work the lever.
A hairy stem may serve the same purpose.

4. The structure of the flower in some cases pre-
vents the entrance of any but an insect large enough to
do the work of pollination. In the snapdragon, for
instance, it requires a heavy insect to depress the lower
lip sufficiently to open a way into the flower.

5. Closure during the hours of light protects the
flower of the evening primrose against many creeping
insects that are abroad in the daytime.

Animals other than insects, as for instance, slugs
and birds, also pollinate flowers, as was seen in the
case of the fuschia.

1. In the clianthus (kaka-beak), the so-called red
kowhai, the tui was originally the chief agent of
pollination. On thrusting his tongue to the base of the
keel, into which the pollen had been shed, he would
cause the brush-like style to sweep out the pollen on
to his forehead. The stigma, which is at the end of
the style, would, however, first strike the bird, so that
it would receive pollen that might have been brought
from another flower.

2. The rewarewa (Knightia excelsa) (Fig. 109)
under natural conditions, is pollinated by tuis and
other native birds. The anthers are pressed close
against vertical grooves towards the top of the style.
Into these grooves the pollen is shed, being well pro-
tected by the perianth tube, which does not open till