Nowhere is the effect on plants of selection and cultivation seen better than in our native fruit-trees. We have only to compare the size, flavour, and almost endless variety of apples and pears with the fruit of the wild stock of these two species--the Crab (_Pyrus Malus_) and Wild Pear (_Pyrus communis_) of our hedgerows--to realize how much has been accomplished. In garden flowers, also, we see most striking results of continuous selection. By taking advantage of the tendency of stamens and carpels to change occasionally into petals, and of petals to increase in number, “double flowers” have been effected. When “doubling” is complete--that is, when the conversion into petals is thorough--no seed can of course be produced, and the plants must be propagated by cuttings. Different other slight natural variations, exaggerated by selection and cultivation, have been the source of innumerable “varieties” in our gardens. Sometimes the natural variation is by no means slight, but of a striking character which the efforts of gardeners have not succeeded in developing further. Take, for instance, the case of fastigiate trees, such as the Lombardy Poplar (_Populus nigra_, var. _italica_) or the Irish Yew (_Taxus baccata_, var. _fastigiata_). These are freaks or sports, the character being that _all_ the branches, not only the leader, tend to assume a vertical position. The Irish Yew originated as a wild “female” (pistillate) seedling found on the hills of Co. Fermanagh about 1780 and never rediscovered. It appears to be a juvenile form, preserving throughout life its seedling characters--a kind of Peter Pan among plants. Of the Lombardy Poplar the origin is not known, but it was no doubt similar. Seedlings of the Irish Yew revert to the ordinary type, and all the Irish Yews in cultivation are pieces of the original plant grown as cuttings. Poplars, like the Yew, bear the “male” (staminate) and “female” (pistillate) flowers on different trees, and the original Lombardy Poplar having been a “male” it also can be propagated only by cuttings--probably seedlings would in any case revert to the usual form. The reverse of this abnormal erect habit is seen in weeping trees, where the branches for unexplained reasons seek to grow downward. In nature this results in a creeping habit. If planted on a height the branches will deliberately grow downwards towards the ground. Cultivators graft such forms on the top of a tall stem of a normal specimen, with the result that we see in the Weeping Ash and similar gardeners’ productions.