6. The rose hip.—Examine fruits of the wild rose. Notice that they are urn-shaped. On the flat rim of the urn observe the five scars left by the sepals (or, in some cases, the sepals themselves). In the opening of the urn see a tuft of greyish hairs. Cut the fruit down from top to bottom through the middle to see the thick, fleshy wall of the urn and the contained nutlets. From what part of the flower is the fleshy wall of the hip derived? Examine a nutlet. What does the tuft of hairs seen in the mouth of the urn consist of? Open a nutlet with a needle and pick out the seed. 7. The strawberry.—Cut a strawberry down the middle and notice at the base the persistent calyx, in the inside the fleshy receptacle, and on the outside the yellowish nutlets. Open a nutlet with a needle and pick out the seed. The help of animals.—It has been seen in Chapter VI. that insects play a very important part in the fertilisation of many flowers. Very many plants also call in the aid of animals at a later stage for the dispersal of the seeds, and the devices by which this aid is obtained are often very ingenious. [Pg 177] Hooked fruits.—Sometimes after a country walk the reader has probably found small fruits and seeds sticking to his clothes. They have become attached to the cloth by means of small hooks which they carry. The fruit of the herb bennet (wood avens) is a good example of this device. When the stigma of the fruit breaks away, a little hook is left at the top of the style (Fig. 138). Goosegrass or cleavers—a common hedgerow plant—and many others have also hooked fruits. Sheep or cattle, grazing near such plants are very likely to brush against them and carry off the fruits and seeds in their hair. They may not again reach the ground until they have been carried far from the place where they grew. The position of hooked fruits.—It is evident that these little hooks would be quite useless if the fruits grew out of the reach of animals. Such hooked fruits are never found, for instance, on high trees. Fig. 138.—A, Aggregate Fruit of Wood Avens (nat. size); most of the stigmas have broken off. a, a, a, fruits with stigmas still attached; c, calyx; B, single fruit with stigma still attached (magnified); C, single hooked fruit after loss of stigma (magnified).