In England there are no very high mountains, so that you cannot study the effect of great heights on plants, but all the same England affords quite sufficient opportunity for the study of physical geography in its relation to plant-distribution. Even in the cultivated fields, where man tries to help the plants to overcome their surroundings, you will find the influence of the soil is very largely felt. Ask any farmer about his land, and he may tell you that a certain one of his fields is specially good for potatoes, another for barley, or that in a village a few miles away they can grow splendid crops of strawberries, while his are not worth the planting. Then think of the different kinds of plants for which the different counties of England are noted. No one could get the produce of the cherry orchards and hop-gardens of Kent to grow on the Yorkshire moors. Nor do we find acres of heather moor on the downs in the south of England, but instead there is a short turf with many little flowers which love the chalk and limestone, such as the blue and white polygala, rock roses, and several small orchids. Now what is the difference between the north and the south of England? It is chiefly one of rock and soil. On the Downs in the south you find a thin coating of brown earth over thick masses of white chalk through the surface of which the water supply quickly runs, so that we get few streams or bogs. In the north the hills are built of coarse sandstones, hard grey limestones, and fine black shales which hold much water, so that there are many swampy places and innumerable streams and little waterfalls. Then, again, the land in the north of Kent, which is so famous for its cherries and hops, is a rich, fine clay, with a muddy and sandy soil, which centuries ago was the bed of a great river, and now is the most important factor in making Kent one of the most fertile parts of England. If we find that the influence of the physical nature of the land is so strong even in the case of cultivated plants, which are helped by man’s knowledge, we shall expect to find that it is still more felt by the wild plants. Let us go, for example, to the moors east of Settle, in Yorkshire, where you find the three kinds of rock, the hard limestone, coarse sandstone, and soft, black shales. If you walk across the moors, you will see that the principal plants are heather, bilberry, and several coarse grasses, which grow in more or less irregular patches. If you notice the grasses carefully, you will find that they are of several different kinds, showing varieties in their size, form of leaf, colour, and so on, and that very frequently the different kinds grow on the different types of rock beneath them. After a little experience, you will almost be able to tell what is the nature of the rock on which you are standing by the appearance of the plants at your feet.