Hazel (_Corylus_), Scotch Fir (_Pinus_), or Reed-mace (_Typha_), we note the small size of the flowers and the great abundance of pollen. Compare these with insect-fertilized flowers, such as Buttercup (_Ranunculus_), Flax (_Linum_), Snapdragon (_Antirrhinum_), or one of the Orchids. In these the flowers are much larger owing to the increased size of the petals, which are of brilliant colour and of various shape. Pollen is mostly much reduced in quantity, since insects flying direct from flower to flower afford a far more economical mode of distribution than is offered by the wind. The pollen grains, moreover, are sticky and covered with tiny spines or knobs, to render them more liable to adhere to the body or head of an insect; the pollen grains of wind-fertilized flowers being, on the other hand, smooth, dry, and dust-like. Again, these insect-pollinated flowers usually possess little glands which secrete nectar, the sugary syrup which by digestion in a bee’s body becomes honey. Here, then, is the inter-relation established: the insect helps the plant by carrying its pollen from flower to flower, and in its turn is helped by the provision of delicious food. And what about the showy petals, and the fragrance that so often marks these entomophilous flowers? They are advertisements, designed to catch the attention of the necessary insects as they fly about. Not only does the corolla by its bright colour attract insects, but markings of various shapes and tints upon the petals are generally held to be honey-guides--sign-posts directing the insects to the nectar and to the pollen. These are especially conspicuous in many of the irregular flowers to which reference will be made shortly, in which the insects are encouraged to approach the flowers in a particular way. An example [Illustration: FIG. 14.--FLOWER OF ERODIUM PETRÆUM. 2/1.] of such markings, as seen in the genus Erodium, is shown in Fig. 14. It is interesting to note the various ways in which flowers render themselves conspicuous in order to attract insects. In the majority of Seed Plants, such as the Buttercup, Pea, Rose, Foxglove, it is the corolla, formed either of separate petals, as in the first three, or of petals fused together, as in the last, which by its bright colour or colours renders the flower noticeable. In other species the calyx takes on the function of advertisement, the corolla being in comparison insignificant--we may study examples of this in the Anemones, Hellebores, and Marsh Marigold (_Caltha palustris_). It is worth examining this last, to see how its coloured _sepals_ resemble and fulfil the same function as the _petals_ of its cousins the Buttercups. Or, again, sepals and petals may combine in showiness, both sets being brightly coloured in one or more tints--compare the Columbine (_Aquilegia_), Larkspur (_Delphinium_), Milkwort (_Polygala_), and the marvellous flowers of Orchids. In the great group of the Monocotyledons, indeed, to which