书城教材教辅科学读本(英文原版)(套装1-6册)
47723000000063

第63章 第一册(63)

hop, are not strong enough to stand upright. We put tall sticks beside them, and they twine themselvesround the sticks. We call them twining stems.""We train the sweet-peas on the trellis for support," said Willie, "but they are not twining plants. They have little curling tendrils here and there, which cling round the trellis. The vine and honeysuckle have tendrils too. We call these climbing plants.""Now come and look at these strawberry plants," said Fred. "See, as the plant grows, it sends out slender stems along the ground. These we call runners. Each runner sends down, at the next joint, a great many new roots. Plants of this kind we call creeping plants.

"I have one more stem to show you," he went on. "We will pull up this root of mint. See, here are the roots. But what are these thick white cords, which run out from the root?

"If you look, you will see buds here and there along the cords. This proves that these cords are not roots, but stems. We never find buds on roots.

"We call stems of this kind underground stems."SUMMARY