TONGUES AND TUBES.
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.
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.
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.
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.