You have heard of men and women who do this sort of thing,—who shirk all trouble, and try to live on the work of others; and I fear you know some boys and girls who are not altogether unlike the dodder,—boys and girls who never take any pains if they can possibly help it, who try to have all of the fun and none of the work; but did you ever suppose you would come across a plant that would conduct itself in such a fashion? Of course, when the dodder happens to fasten itself upon some wild plant, little harm is done. But unfortunately it is very partial to plants that are useful to men, and then we must look upon it as an enemy. Linen is made from the flax plant, and this flax plant is one of the favorite victims of the dodder. Sometimes it will attack and starve to death whole fields of flax. But do not let us forget that we happen to be talking about the dodder because it is one of the plants which put out roots above ground. [Illustration: FIG. 119] There is one plant which many of you have seen, that never, at any time of its life, is rooted in the earth, but which feeds always upon the branches of the trees in which it lives. This plant (Fig. 119) is one of which perhaps you hear and see a good deal at Christmas time. It is an old English custom, at this season, to hang somewhere about the house a mistletoe bough (for the mistletoe is the plant I mean) with the understanding that one is free to steal a kiss from any maiden caught beneath it. And as mistletoe boughs are sold on our street corners and in our shops at Christmas, there has been no difficulty in bringing one to school to-day. The greenish mistletoe berries are eaten by birds. Often their seeds are dropped by these birds upon the branches of trees. There they hold fast by means of the sticky material with which they are covered. Soon they send out roots which pierce the bark, and, like the roots of the dodder, suck up the juices of the tree, and supply the plant with nourishment. Then there are water roots as well as earth roots. Some of these water roots are put forth by plants which are nowhere attached to the earth. These are plants which you would not be likely to know about. One of them, the duckweed, is very common in ponds; but it is so tiny that when you have seen a quantity of these duckweeds, perhaps you have never supposed them to be true plants, but rather a green scum floating on the top of the water. But the duckweed is truly a plant. It has both flower and fruit, although without a distinct stem and leaves; and it sends down into the water its long, hanging roots, which yet do not reach the ground. There are other plants which have at the same time underground roots and water roots.