Some flowers will not be fertilised at all by pollen from their own plant, and one of these is clover. Mr. Darwin, a scientist who has taught us a great deal about this subject, tried an experiment in which he fertilised twenty heads of clover by the pollen of other clover plants. They produced no less than 2290 seeds, but when another twenty heads of clover were kept from being fertilised by any but their own pollen, not a single seed was produced. No doubt you will be wondering why a flower is not fertilised when anthers covered with pollen surround the stigma. The explanation is very simple, for the stigma has to become ripe before it can receive any pollen. In some plants the stigma is ripe before the anthers give off pollen, whilst in others all the pollen is given from off the anthers before the stigma becomes ripe. Thus we see how Nature prevents a flower from fertilising itself. CHAPTER XLII BEES AND FLOWERS From what you have read in the previous chapter you will see that for a flower to be fertilised the pollen must come from another plant. How, then, is this effected, for plants cannot walk to one another and ask for each other’s pollen? There are two ways in which Nature’s law can be fulfilled. The first is by the wind, for the pollen of some flowers, such as the willow-catkin, may be blown on to the stigmas of other catkins, and thus fertilise them. The stigmas of such plants are made branched and hairy, so as to allow of their more easily catching the flying pollen as it passes. You will easily understand that it would not do for all plants to be wind-fertilised, for the chances of pollen grains alighting on stigmas would be very remote if that were the case. By far the greater number of plants, therefore, are fertilised in the second manner, which is by insects. The bees are the most useful of all, and we now see what service they render to plants, for when a little worker dips into a flower in search of nectar, her body becomes covered with pollen. It may be that the next flower she comes to is one in which the stigma is ripe, so that the bee, as she pushes her way in, rubs her pollen-covered body against it, and thus the flower is fertilised by pollen from another plant. When a bee is nectar-gathering, you will notice that she always keeps to one kind of plant on each journey, just as the pollen gatherers do. This arrangement fits in with Nature’s plan, for it is thus that pollen of the sweet-pea is carried to another sweet-pea, and not to a wallflower, and so with each kind of plant. Many people think that the beautiful colours and scents of flowers exist only to delight man, but this is quite a wrong idea. For instance, just think of the gorgeous flowers which must grow and die in places where no human eye ever sees them. The real state of affairs is that man uses the flowers which already exist, and even if all men were to die, flowers would still continue to blossom.