“It has tendrils ‘instead,’” said Frank.
“Exactly!” said Uncle George. “These tendrils correspond to leaflets. Now, if the plant has been forced to turn all its leaflets, except two, into gripping organs, how does it manage to make up for this loss of green leaves?
Young Edible Pea.
“We have already learned that plants take in food from the air by means of the green substance in their leaves. The more of this green substance a plant possesses, the more food it can take in from the air. If it sacrifices leaves in order to climb up to the light and air, its amount of the green material must be lessened. But the sweet-pea makes up for this loss of leaves. Can you see how it does so?”
“The stipules are very large,” said Frank.
“And the lower part of the leaf-stalk is very flat, broad, and green,” added Tom.
“Very good,” said Uncle George, “but look at the long, slender stem. It has flat, green, ribbon-like outgrowths on each side throughout its whole length. So, you see, what the plant loses in leaves, it makes up in another way.
“Let us now look at the ordinary pea plant. Its leaf has four pairs of leaflets and three pairs of tendrils besides the terminal tendril—seven tendrils altogether. The stipules here are also very large—much larger than those of the sweet-pea. But the stem is round and smooth. There are no green outgrowths. Here is a wild pea, which I found to-day, which has no leaves at all. All its leaflets have been turned into tendrils or gripping organs. But look at the enormous stipules it has! They are much bigger than ordinary pea leaves.
