Pea-vines are held up in a different way. Little tendrils are put forth which wind around the branches of the bushes that are set for the vines to run up on. These tendrils clasp very tightly. You see them on many kinds of vines. You see them on grape-vines, and on the vine of the passion-flower. Sometimes the tendrils go out from the ends of the leaves. You see a leaf of this kind on page 68.
Thunbergia.
A vine called thunbergia is held up in a very queer manner. If a leaf happens to come near a twig or a string it twists its stem around it. So the stems of the leaves act as tendrils to support the vine.
Trumpet-creeper.
The vine of the trumpet-creeper is supported in a singular way. Whenever it touches any thing there come out at the joints of the stalks some sprawling things like the feet of a spider. These feet fasten themselves very strongly to whatever the vine is running on. If it runs up the side of a board fence, these feet mix up their fibres very tightly with the fibres of the wood. It is curious to observe that where any part of the vine is not against any thing these feet do not appear. They are made only where they can be used. The plant acts just as if it knew where it could use them.
Questions.—What is the difference between stalks and trunks? Why does a tree need so strong a trunk? Why do the stalks of plants have no wood in them? What is said of the flinty earth that is in some of them? In what ways is the flint in straws of use? What is said of the scouring-rush? How does flint get into any plant? Why does it not go into the kernels of grain as well as into the stalks? What becomes of stalks that are not woody in the winter? What is said of the woody stalks of shrubs? What are vines? How is the bean-vine supported? Tell about tendrils. What is said of the thunbergia? Describe the way in which the trumpet-creeper is supported.
CHAPTER XXVII.
THE BARK OF TREES AND SHRUBS.
In the trunk of a tree or the stalk of a shrub there are three parts. They are the bark, the wood, and the pith.
The outer bark of a tree its coat.