How a Tree Grows—The Horse-Chestnut

When a young tree has made plenty of wood and branches, it begins to use some of its buds for making flowers. These buds grow in the same places as leaf-buds. In some trees they grow where the leaf joins the stem. In others they grow at the tips of the twigs. They are generally rounder and less pointed than the leaf-buds.

The flowers of the oak are very small, so you had better look out for a horse-chestnut tree and gather a bough for this lesson. You will find buds on a horse-chestnut tree almost any time in the year, except when it is in full leaf, and then they will be very small.

The best time to look is just at the end of the winter, when the tree is bare. First notice the smaller buds, which grow two and two opposite each other along the twig. You will see below each bud a scar marking the place on which the leaf grew last year. This scar is shaped like a horseshoe, and has several black spots on it arranged like the nails. These spots show where the bundles of tubes were, which carried the sap into the leaf.

Now pick one of the buds to pieces. They are small, and you will not find it very easy, but you can take off the brown sticky scales, and you will find inside, first some soft gummy down, and then the young green leaves, tightly folded together, with a green growing tip between them.

So if you had left that bud, and it could get food enough, it would have grown into a small branch in the spring, with leaves on it. But it is very seldom that all  the buds on a branch grow. The stronger ones take the food, and the weaker ones either die or wait till next year.

Twig of Horse Chestnut

Now look at the buds on the tips of the branches. They are very much larger than those growing on the sides, and you can examine them easily. When you have taken away from twelve to seventeen sticky scales, you will come to the same kind of soft white gummy down which you found in the leaf-buds, making a warm bed for the tender growing parts inside.

But this bud is not all leaves like the smaller one. It has four small bright green leaves, and wrapped up inside them is a tiny spike covered with little knobs (F).

You cannot examine the flowers on this spike without a microscope. But if you wait and watch till May, you will see others like it gradually opening out into a lovely branch of flowers, and I think you will like them all the better for knowing how the tree prepared them last autumn, when it was covered with leaves, and wrapped them up warm all the winter in sticky buds.

And while you are waiting for the flowers, look at the tree itself. The trunk is smooth and round. The branches begin to grow out of it about ten feet from the ground. They grow two and two opposite to each other like the leaves, except where a bud has failed. The lower branches, which of course are the oldest, stretch out farthest, so that the tree rounds off very gracefully up to the top.

Then, as April comes, the brown scales fall from the leaf-buds, and the tree is covered with bright green downy leaves. They are each cut into seven leaflets, which hang down from the tip of the leaf-stalk like a half-opened umbrella. Little by little, as they grow stronger, they rise up into a broad leaf with seven fingers. It is while they are doing this that the flower-buds throw off their scales, the four green leaves open out, and the flower spike begins to hang out its snow-white flowers, streaked with pink and yellow (see p. 10).

The flowers nearest to the branch open first and grow strong. They are perfect flowers, with five green sepals and five beautiful crimped petals, and have both stamens and seed-box inside. These will form the chestnuts which ripen in the autumn. The flowers nearer to the tip of the spike have only stamens inside the petals. They wither away as soon as they have shed their pollen-dust.

Horse-Chestnut Flower and Fruit

If you can get an old flower spike when the flowers are withered, and cut the seed-box of a flower across, you will see that it has three divisions with two little seeds in each. But when you pick up the prickly fruit in the autumn, though it burst into three parts, there are generally only two horse-chestnuts inside (see p. 10), with another very tiny one. The two big seeds have starved out the other four little ones and grown big and strong. If the chestnuts are brown and shiny, they are ripe, and will grow if you sow them.

Though the horse-chestnut is very beautiful in the summer, its leaves turn yellow very early and fall in August, and then you can see the buds already formed for next year. All boys know that horse-chestnuts are bitter and not good eating. The sweet chestnuts, which we roast, come from quite a different tree, and are not seeds, but fruits.

Bring a branch of horse-chestnut and examine the buds. Find a flower spike in May; look at the ovary in June, and the fruit in September.