HOW FLOWERS PROTECT THEIR NECTAR
A whole volume could be written on the marvellous contrivances of
flowers, but we must be content to describe a few. It is a wonderful
subject, and one which you yourselves will be able to study quite
easily.
Have you ever wondered why cup-shaped flowers--the harebell, the
snowdrop, and many others--droop their heads? It is because they would
become filled with rain or dew if they did not do so, and thus their
nectar would be spoiled, and insects would no longer visit them. For
the same reason daisies will close their petals when dark clouds come
up, and will remain closed until the sun shines again. Have you ever
seen a flower of the white dead nettle? It actually protects its
nectaries with one of its petals, which overhangs the others, and acts
like a little umbrella.
The ordinary nasturtiums (Plate XXXVII.) have the edge of the three
lower petals cut into fine strips. These keep the rain from the nectar,
which is situated at the end of the long spur. You will notice that
hive bees are not often seen on nasturtiums, for their tongues are
not long enough to reach the nectar; so these flowers depend more
on humble-bees for fertilisation. The nasturtium is a flower which
illustrates very well what was said about “honey-guides” just now, for
all the lines on the petals point to where the nectar is to be found.
Some flowers have to protect their honey from certain insects, who
wish to take it without fertilising the flower in return. Ants, for
instance, are very fond of honey; and, as you can easily imagine, they
are so small that they can creep right down to the nectaries without
dusting themselves with pollen, or fertilising the flower. So certain
flowers--like the primrose--have their stalks covered with multitudes
of tiny hairs. These serve as a barricade to the ant, and prevent it
from climbing to the flower above. The cross-leaved heather has its
stalk and calyx covered with sticky hairs, so that not only are the
little thieves prevented from getting to the flower, but they are
actually held prisoners as well.