Fig. 113. A piece of leaf of Bladderwort showing the bladders on the branches.
There is one more animal eater which you must try to see, which grows in the water of slow-running streams and in ponds. It is the bladderwort, on which we find very many tiny bladder-like structures on the finely divided leaves under the water. The bladders are built on something of the same plan as a lobster pot, with bristly hairs pointing into the entrance, across which there is a little flap, which makes it quite easy for the very minute animals living in such abundance in the water, to swim into the bladder opening, but extremely difficult or almost impossible for them to swim out again (see fig. 114). So there they must finally die, and their nourishing juices are absorbed by little compound hairs, many of which are developed on the inside of the bladder.
Fig. 114. A single bladder of the Bladderwort, much enlarged, showing the pointed hairs and the flap at the opening.
In the tropical countries there are many kinds of “pitcher plants” with wonderful soup-kettle-like pitchers which catch insects. You may be able to see these plants in a big greenhouse, and should certainly find them in every botanical garden. Notice how large the pitchers are, and that they are really modified leaves which have become different from the other leaves of the plant because of their special work. They generally contain a considerable quantity of water as well as the flies they have caught, and are really “stock-pots” which keep the plant supplied with nourishing, ready-made food in addition to the food which it builds for itself in the green leaves.
Fig. 115. Pitcher leaf of Nepenthes, which acts as a “soup-kettle.”