Fig. 86. A Bur, which is a cluster of hooked fruits.
Fig. 87. Simple fruits: (a) of the Goose grass with its hooks; (b) the Bidens with its harpoon-like spines.
Fig. 88. Strawberry. Each of the little “seeds” is a whole fruit, and the “flesh” the swollen receptacle.
Quite a special kind of fruit is the strawberry, which, as you know, has a thick fleshy pulp covered with a number of small, yellow “seeds.” In reality, each of these “seeds” is a whole fruit, and the thick flesh which we eat is the swollen end of the flower stalk which we call the “receptacle.” Therefore a strawberry really consists of a large number of fruits and a piece of stalk which is altered to form the fleshy, attractive mass which induces birds and people to eat the whole, and so scatter the little dry fruits.
There are very many other kinds of fruits which all have special devices to make sure that their seeds are scattered, and all proper fruits have seeds in them. But, just as we found that some garden flowers are grown only for their beauty, and do not set any seed, so we find that some fruits are grown specially without any seeds, such as bananas and some oranges. Such fruits are the result of our liking to eat the soft, sweet pulp without the trouble of the seeds, but such fruits are of no use to the plant.