Part 7

In May the Birch tree is in flower. You know that tree flowers are not so easy to see as meadow flowers: they require to be sought for and looked at carefully if you wish to know about them. The Birch tree has two kinds of flowers, and both are needed if the seed from which new trees may grow is to be made ready. It takes the tree a whole year to prepare one kind of flower. During summer look at the foot of a leaf stalk, where it joins the twig, and you will find two tiny green stamen catkins (4) with all their soft scales tightly closed together. In autumn these little catkins become dark purple, and they hang on the tree all winter. Early in the following spring they change entirely. The scales unclose and the catkins grow longer till they look like a pair of caterpillars loosely shaking in the wind. Behind the scales in these reddy-brown caterpillars you find a mass of flowers, each made up of one tiny sepal, also two slender stamens with small yellow heads.

Now look at the other kind of flower, the seed catkin (3). These also are small and green, but they grow singly and are fatter and rounder than the stamen catkins. Their scales never open very wide, but if you look closely you will see behind each scale three little pear-shaped seed-vessels with two slender horns standing up from the top of each.

When the seeds in this catkin are ripe they resemble tiny nuts with wings on each side (5): and on windy days you can see clouds of these little winged seeds (5a) fluttering to the ground like small flies. Birds are very fond of Birch tree seeds, and one kind of finch, the siskin, is usually found hovering among the Birch trees.

The Birch tree lives till it is about a hundred years old. It is not grown up till it is twenty-five, so you will find no seeds on the young birches. It is a tree with many useful qualities. The bark is sometimes twisted into torches, as it contains a good deal of oil, and it is also used in tanning leather. The delicious scent of Russian leather is due to Birch bark oil. And there is sugar in the sap which may be made into wine. Furniture is largely made from the prettily grained Birch wood.

PLATE IV

THE ALDER

The Alder tree (1) is a cousin of the Birch and the Hazel, and like them its flowers and seeds are borne in catkins. It is usually to be found growing by the side of a slow-running stream, over which its slender branches bend gracefully, while its spreading roots cling to the boggy soil at the water’s edge. For the Alder does not thrive in dry ground: it is a water-loving tree, and its many tiny roots attract moisture, and suck it up greedily; so that the ground where the Alder grows is often a marshy swamp.

Sometimes you will find an Alder which has grown into a lofty tree with a rough brown-black bark, and with many large branches; but it is much more frequently found as a low-growing and rather gloomy bush, about the same size as the Hazel.

The wood of the Alder is much sought after for buildings which stand in water. In Venice one of the most famous bridges, the Rialto, is built on piles, or great posts of Alder driven deep into the bed of the canal: and one reads in old history books that boats were first made of the trunks of the Alder tree. But it is of no use for fences or gate posts, as it decays quickly in dry soil.

THE ALDER

1. Alder Tree 2. Leaf Spray 3. Stamen Catkins 4. Seed Catkins 5. Last Year’s Seed Catkins 6. Next Year’s Seed Catkins]

If you watch a woodman cutting down an Alder tree you will notice that the chips which fall under his axe are very white; but soon they change colour and become a reddish pink. The hard wood knots which are found in the tree trunk are beautifully streaked and veined and are much prized by furniture makers.

In early spring you should walk to the banks of a stream and look for an Alder tree. Like the Hazel, you will easily know it by its winter catkins, though these are very different from Hazel catkins. Clinging to the boughs you see groups of small brown oval cones, which are quite hard and woody and which snap off easily. These woody cones are the withered seed catkins (5) of last year. As well as these you find bunches of long drooping caterpillars with tightly-shut purple-green scales, which will not unclose till the spring days come. These are the young stamen catkins, and they have taken six months to grow so far. By these you will always know the Alder tree; and it is most interesting to watch day by day how its catkins grow and change.

In spring the tree produces many groups of tiny seed catkins (4), which are hard and oval and covered with closely-shut green scales. As the days get warmer these cones grow larger and larger, and one day you will find the scales opening as a fir cone does when it is ripe. Underneath each scale are hidden two seeds, and from the top of each seed rise two slender horns. There are no wings to the seed, as in the Birch tree. These seed cones grow fatter and larger all summer, and by autumn their scales, instead of remaining green and soft, have become a dark reddish brown colour and are hard and woody. In October or November the seed is quite ripe, and is shaken on to the boggy ground below. Then the empty seed catkins become dry and shrivelled, and they remain in groups clinging to the twigs all winter.

But the drooping caterpillars have been growing and changing too. Soon after the seed catkins have unclosed their hard oval balls, so that the sun and light may reach their tiny seeds, these drooping stamen catkins (3) unclose, and their scales take on a deeper shade of reddish purple. Each scale is edged with three points, and each point covers four tiny stamens and four tiny petals. When the fine powder in the yellow stamen heads is ripe, the wind blows it from the dangling tails on to the seed cones which are waiting for it, as without the stamen powder the seeds would never ripen: and soon after this happens the dangling tails fall to the ground.

THE HORNBEAM

1. Hornbeam 2. Leaf Spray 3. Stamen Catkin 4. Seed Catkin 5. Fruit]

If you look at an Alder tree in late autumn you will find three kinds of catkins. First, the empty seed catkins with dry woody scales; second, the dangling stamen catkins with the fine stamen dust all blown away; and third, there are tiny little caterpillar catkins with their scales still tightly closed together--these are next year’s stamen catkins (6) just begun to form.

The leaves (2) of the Alder are heavy and leathery. They are usually rounded at the tips, but sometimes they are square, as if a piece had been cut off. Each leaf is prettily toothed all round the edge, and the veins, which run from the centre rib to the margin, are very much raised. When the leaves are newly opened, the under-side is covered with tufts of soft down, and they are slightly sticky. Sometimes they are tinged with dull purple. These leaves are placed alternately on the stem, and while still in bud each leaf is enclosed in a pair of oval sheaths like small yellow ears. These ears do not fall off when the leaf unfolds, as do the leaf coverings of the Birch and the Beech; you will often find them at the bottom of the leaf stalk when the leaf is fully grown.

PLATE V

THE HORNBEAM

This is a tree that many people tell you they have never noticed; even people who know the names of most of our forest trees look surprised if you ask them which is the Hornbeam (1); they have never heard of it. And yet it grows freely in England in the woods and hedgerows, and like the Beech it is invaluable for sheltering with its close bushy branches younger trees that are struggling to live. If left to grow in good soil the Hornbeam will become a tall tree over seventy feet high, but it is not usual to find such well-grown Hornbeams, because the tree is generally planted to form hedges, and as these require thickness and bushiness rather than height, the top of the tree is often cut off, so that all its strength may go to producing side-branches.

Last century it was the fashion to have curious puzzle-paths made in gardens. You entered at a gap in a leafy hedge and walked on and on, and in and out between growing hedges till you came to an open space in the centre. Then the puzzle was to find your way out again, and this was sometimes very difficult. This kind of puzzle-path was called a maze, and the hedges of these mazes were frequently made of Hornbeam, because this tree will allow itself to be clipped and cut into any shape, and if its tall spreading branches are taken away, it at once puts out many small side-shoots which form a thick hedge.

The Hornbeam branches have a curious habit of growing together where they cross each other. You may find two good-sized branches which are separate on the lower part of the tree, but higher up they cross and touch each other, and frequently they join together and become one branch.

In the town of Ghent in Belgium there is a winding walk arched with Hornbeam: the trees have been planted so close that they meet overhead, and they have then been clipped and cut till they form a green tunnel under which you can walk for three hundred yards.

The trunk of the Hornbeam is a dull grey colour, and it is marked with white spots. It is not round, as are most tree trunks, but looks as if it had been slightly flattened, and so made oval when it was young. The leaves are not unlike those of the Elm and the young Beech, and when the tree is young it is sometimes mistaken for one or other of these. But you will notice some differences if you look carefully.

The Hornbeam leaf (2) is oval and tapers to a sharp point. It has strongly-marked veins running from the centre to the edge of the leaf, and these veins stand up like cord on the under-side of the leaf. You remember that the Beech leaf was smooth and glossy, and that the Elm leaf was rough and hairy? The Hornbeam comes just between the two: it is too rough to be a Beech leaf, and is also too pointed, and it is too smooth to be an Elm leaf. Besides, the two sides of the Hornbeam leaf meet exactly opposite each other on the leaf stalk, and in the Elm the one side of the leaf very often joins the stalk farther down than the other: the leaf is lopsided.

The Hornbeam leaves have two rows of teeth round the edge, and in autumn they turn yellow, and this yellow colour changes into red-brown as the winter draws near. In sheltered places the leaves will hang on the branches all winter, till in spring they are pushed off by the young leaf buds.