[Illustration: [Flower Tube]]
A flower tube is a most convenient and safe place to keep stamens and
nectar. If it is protected by scales or hairs or a sticky juice, as is
often the case, the ants and other small insects are given a gentle but
convincing hint to keep out. They might readily infer their presence is
not wanted, and though it may hurt their feelings a little, they have
nothing to do but obey.
Some flowers like ants and little crawling insects, but they have open,
spreading corollas with the nectars easily reached; but you may be sure
a flower with a tube is no friend to them.
Its tube says “keep out” as plainly as though it had put out a printed
sign, and then a tube is a sign anybody in the insect world can read, no
matter what language he may speak or whether he knows his letters.
But tubes are not intended to keep _all_ visitors away,—far from it.
They are as much an invitation to one kind of insect as they are a
request to “keep off these premises” to another. If you happen to be a
large insect with a long tongue, you will be sure to find a welcome in
many a flower with a tube. And no doubt, if you are fond of honey and
are industrious about collecting it, you will find that the flower whose
nectar you like the very best and which you visit the oftenest has a
tube just the same shape and size as your tongue; and what is more, it
will be in the most convenient position for you to reach it.
It seems to be _your_ flower, and no doubt it is, for flowers have a way
of making their tubes to fit the tongues of those who love them best.
Not that they do _all_ the fitting, for no doubt the tongues also grow
to fit the flowers.
Of course other insects with similar tongues can get the honey too, and
a good many, whose tongues are quite different, can reach more or less
of it; but the bulk of the honey is for the favorite visitor. He can
reach clear to the bottom of the nectary, and in some cases, where the
favorite insect has a very long and very slender tongue, the spur, or
tube, will be so long and slender that none but that particular kind of
insect can get the honey at all.
Everybody who lives in New England, and a good many who do not, knows
the white azalea, often called swamp honeysuckle.
Swamp honeysuckle and the large night-flying moths are great friends.
The azalea has provided honey for the fellows, and protects it, too,
against other visitors, all but the bees and humming birds. The humming
birds are welcome, and the bees have a way of coming whether they are
welcome or not.
If you go just at dark to where the azaleas are blooming, you will not
see the moths, but you will hear them. The chief sounds in the woods are
the rustling of twigs and leaves in the breeze, the calling of frogs
from the ponds, the noises of the insects, and the voices of the
night-flying birds. Then all at once there comes another sound,—a steady
buzz-z-z that draws nearer and nearer until it seems to be close to your
ear. This is the moth come to visit the honeysuckle. And, no doubt, the
honeysuckle is glad to feel the breeze of these fanning wings and feel
the long tongue enter the tube, for the moth’s body touches the
out-reaching stigma and leaves there pollen from some other flower whose
honey it has enjoyed. From the stamens it detaches pollen grains to
carry to another flower; and this, too, no doubt, gives happiness to the
azalea, for it makes its pollen, not for its own use, but for the sake
of its azalea friends.
[Illustration: [Azalea]]
You see, the azalea has long, upturned filaments that reach far out of
the tube, and the style is yet longer, so that only a large insect or a
humming bird, collecting honey while on the wing, can really give pollen
to the stigma.
Bees alight back of the anthers and take the honey. If they want pollen
they collect it from the stamens without touching the stigma, except
once in a while by accident, as it were. So however much the majority of
flowers may love and respect the bee, our azalea has no liking for her.
Besides, the bee has a bad habit of biting a hole in the flower tube and
getting the honey that way. This would be a thoroughly disreputable
performance on the part of any insect, and if bees are not ashamed of it
they ought to be.
The azalea does several things for the moth it loves. It may be its
beautiful white color is for his sake; anyway, if the flower were not
white the moth would not be likely to find it, since he flies abroad
after the birds have gone to rest,—that is, in the evening, when it is
dark in the damp thickets where the honeysuckle loves to grow. Azalea
has a sweet white corolla with a long, slender tube containing nectar
that moth or humming bird can reach, but which bees cannot reach. Watch
a bee try some time. If the flower is between you and the light, you can
see the bee’s brown tongue through the flower tube; she appears to be
standing on her toes and reaching in as far as she can; she darts out
her tongue to its full length, and you can see it wriggling and
straining to get to the abundant honey low down in the flower tube. But
there is no use trying; the tongue is too short and the tube too long.
The honeysuckle tube was not made to fit the bee’s tongue, and the bee
can get only the outer rim of the honey. Perhaps this is why the bee so
often breaks in the back way.
Besides being white, the azalea flowers grow in clusters, which makes
them yet more visible in the dusk. They exhale a delicious and
far-reaching perfume too, and this is a note of invitation to the moths.
[Illustration: [Honeysuckle]]
Instead of writing a note on a sheet of perfumed paper, the honeysuckle
simply sends the perfume without the paper, and the moth understands the
message and knows the white azalea “requests the pleasure” of his
company that evening, and he puts on his best manners, since he cannot
change his clothes, and goes.
The white azalea is so _very_ sweet and so pretty, it would not be
strange if other uninvited guests than bees were to visit it. No doubt,
the ants and bugs and gnats and flies would be glad to, but the azalea
has a very inhospitable way of receiving such would-be guests. All over
the outside of the lower part of the white tube and running in a line to
the very tips of the petals are tiny white hairs with black tips.
These are azalea’s body guard. Each tip exudes a drop of sticky liquid.
Fine, sticky hairs cover the stems and the leaves too; so the
unfortunate insect that tries to crawl up to the flower is sure to get
wings and legs hopelessly entangled and stuck together.
Only large fellows, like bees, who are strong enough to pull themselves
free and clean off their legs, are able to defy this body guard. You
will sometimes meet our sweet azalea covered on the outside with little
marauders who wanted to steal her honey but could not, because the body
guard caught them and stuck them fast.
Not all flowers with tubes have succeeded as well as azalea in keeping
their honey for the visitors who can do them the most good. Yet many
have tried.
Look at the morning-glory, for instance; it has hairs at the entrance to
the nectaries which the ants cannot readily pass, but which the bees can
push aside. The openings to the nectary are large enough readily to
admit the tongue of a bee, and the distance into the nectar is about the
length of a bee’s tongue; but there are no sticky guards to preserve the
honey, for the bees and small beetles and other tiny insects often crawl
into the tube and eat the honey and even devour the flower itself.
[Illustration: EVENING PRIMROSE.]
Tropæolum has a fine large tube full of rich honey for bees and humming
birds. This tube no doubt corresponds to some tongue or bird-bill in her
own South America. But in our country the bees answer very well. The
bumblebee is fond of Tropæolum honey and fertilizes the flower, while an
occasional ruby throat may be seen taking a sip.
Jewelweed’s horn is a humming bird tube and a bee tube, too. The flowers
are so delicately balanced on tiny stalks that wingless insects would
not find an easy entrance.
Pelargonium, too, has a tube suited to some long and slim-tongued
visitor. In her own native land in far-away Africa she probably loves
the butterflies that live there, who also love her, and so they have
grown tongue and tube to fit each other. For the flower is not the only
one to change: the insect changes to suit the flower at the same time
that the flower changes to suit the insect. They grow to fit each other.
Wherever you see a flower tube you may be sure there is somewhere a
tongue to fit it.