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. [Illustration: PLATE V 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.