A Wild Pea with no Leaves. Young Sweet-Peas have no Tendrils.
“Let us now look at the tendrils of the sweet-pea, and see how they grip their supports. Notice that they begin to twist long before they reach the supporting twig. Then, when they have reached it, they twist round it in the opposite way—just like a piece of string, if you twist it at one end, it untwists at the other.”
“Can you see any reason for this coiling before it reaches the twig?” As he spoke, Uncle George pulled a sweet-pea plant out from its supports, and the boys saw that the tendril was really a spiral spring. The plant could be pulled out a considerable length without breaking the tendril.
“You see,” Uncle George continued, “if it were not for that first coiling of the tendril—that is to say, if the tendril grew out straight and only began to twist when it reached the twig—the first breeze of wind would snap the plant from its supports and it would fall to the ground.
“Look now, at the young sweet-peas which we grew in the pot. They are without tendrils of any kind. This shows us, I think, that the sweet-pea was at one time a small plant, like its relative the clover. It grew in open places and did not have to struggle for light and air. But, by and by, when strong growing plants took up the soil, it became forced to produce climbing organs or become choked out. And, having turned its leaves into climbing or gripping organs, it made up for the loss of leaves by producing large stipules and green out-growths to stem and leaf.”
Exercises on Lesson V.
1. Draw a leaf of the wild rose and one of the sweet-pea side by side. 2. Make a list of all the climbing plants you know, and state how each climbs. 3. Look for stipules on the apple, pansy, and bean leaves—make sketches. 4. Those plants of the pea family which have many leaflets have smooth round stems. Those which have few leaflets have “winged” stems. Can you explain this?
VI.—THE GREAT WATER BEETLE.
During summer the boys paid many visits to the horse pond. Each time they went there they saw something to interest them.
Their uncle taught them to keep perfectly still while looking into the water. They soon came to know that this was the best way to study pond-life, for, whenever they moved, the creatures they were watching would dart out of sight.