“Some time ago,” said Uncle George, “I promised to tell you something about how plants arm themselves. And here, in this hedgerow, we have some good examples of armed plants.”
“There is the stinging nettle,” said Tom, pointing to a large patch at the roadside.
“The stinging nettle is certainly well protected,” said his uncle. “You have only to touch any part of it lightly with your hand to find that out. Every part of the plant is covered with small needle-shaped hairs. These hairs are hollow and contain a poisonous juice. At the base of each hair there is a bag filled with this juice, while the tip of each is sharp and very brittle.
“When your hand touches a nettle—unless you grasp it tightly—the sharp hair pierces the skin. It’s brittle point breaks off and the poisonous juice is poured out.”
“Why is the nettle covered with these horrid stings?” asked Frank.
“To save it from being eaten up, of course. The nettle is a tender and juicy plant, and, if it were not for its stings it would soon disappear altogether.
“Now, here is another armed plant, the blackberry or bramble. The stem and also the backs of the leaves are covered with large curved prickles. These prickles not only protect the plant from grazing animals, but they help it to climb and scramble up walls and hedges.
“If you try to pull a bramble branch down out of the hawthorn hedge, you will find it rather difficult, for its large prickles are all turned one way. They are really sharp hooks.”
“Here is a wild rose bush. It is also covered with large hooked prickles,” said Frank.
“Yes, Tom, and, like the bramble, it threads its way among stronger and taller plants.