When you were picking the flowers of the peas and scarlet-runners, if you kept your eyes open, you must have noticed that they climb up the sticks which we put for them. But I daresay you did not ask yourself why they climb, nor how they climb.
You know that if you took the sticks away they would fall in a tangled mass on the ground. For peas and scarlet-runners have thin weak stems. They could not get enough light and air all tumbled together on the ground. They would be stifled under other plants. So they have learnt to climb up on a hedge or sticks, or anything they can find, to lift them towards the sky.
That is why they climb, now let us see how they do it. For they do not both set to work in the same way.
You will find on the pea-plant that in many places where a leaf ought to be, there is a little curled green thread, which clings round the twig of the stick, just as a baby clings to its mother's finger. We call these threads "tendrils." They hold the plant up to the light and air, and let the blossoms hang out where the bees can find them. The scarlet-runners do their climbing differently. They do not use their leaves, but twine their whole stem round the sticks.
If you look along the hedges you will find many climbing plants, which manage to use the thick bushes as a sort of bank on which to spread out their leaves and flowers. There is the Clematis, or Traveller's Joy. It has not turned its leaves into tendrils, nor twined its stem. It twists the stalk of the leaves tightly round the twigs, so that the leaves stand out at the end. Its pretty greenish flowers are spread in this way all over the top of the hedge, and by-and-by the feathery seed-boxes will hang like an old man's beard, just where the wind can catch them to blow them away.
I think you must know the Goose-grass or Cleavers, which grows over everything in the lanes. Its narrow green leaves are arranged round the stem like a star, and it has very tiny white flowers. The stem, leaves and seed-boxes are all crowded with tiny hooks so that it clings to your hand when you gather it. It is really a very weak plant, but it clings to other plants which are stronger, and so raises itself up.
The blackberry and other brambles climb in the same way, and the wild rose climbs by its thorns. Further along the hedgerow the wild Hop may be growing. Its stems die down every year and grow up again in the spring. Yet it manages to spread a long way, for its stem twines round twigs and small trees, and everything it can find, spreading out its broad leaves shaped like a heart. You will find the flowers of the hop rather puzzling, for its dust-bags and seed-boxes grow on different plants.
The Honeysuckle, too, twines its stem, as you must have seen on the porch or the paling. Sometimes when it twines round a young branch, it winds itself so tightly that the branch cannot grow in the places where the honeysuckle binds it. So it is marked all the way up, as if it had a ribbon round it.
Then there are the pretty plants called Tares or vetches, which have flowers like small pea-flowers. They climb everywhere by their tendrils. I think you will be able to find all these as well as the Convolvulus or bindweed, which twines round all plants, even our gooseberry and currant bushes, and wants weeding out very carefully. But I am not quite sure whether you can find a curious plant called the Dodder. You must look for it on the common, climbing over the heath and gorse bushes. It is only a thin wiry stem, with clusters of tiny pink flowers on it. It has no leaves at all. How then can it live since it has no leaves to make food? It twines round the gorse, or heath, or clover, and sends its roots into their stems and sucks out ready-made food!
The Vine and the pretty Virginia creepers turn their small branches into threads for climbing. Very likely you have a Virginia creeper on your wall, which turns red in the autumn. Two kinds of this creeper have a very curious plan for climbing. When the threads, or tendrils, touch the wall, their tips turn red, and swell into little cushions. These cushions stick so fast to the wall that even when the branch is dead you have to pull them off. Lastly the Ivy climbs by small roots, which grow all along the stems.
Now you know all the four dodges which plants have for climbing. By hooks, by threads, by their roots, and by the whole plant twining itself round. Try to see how many you can find.
Bring one of each kind of climbing plant.