The successful cultivation of plants requires a close familiarity with their likes and dislikes, a knowledge of the conditions of their existence, and how to meet those conditions to the best advantage of the cultivator; for the requirements of man are not always identical with the objects of the plants themselves. By dint of practice alone and close application to the art for a series of years one may become sufficiently expert to grow a limited number of kinds to great perfection, but the field for experiment and improvement is boundless in the domain of gardening. Not merely are there plants, flowers, fruits, and vegetables with which one is familiar, but new ones are constantly arising, differing in some respect from those that preceded them; and hundreds of others, whose cultivation is an undetermined quantity, or may have been known to the successful growers of bygone times and since forgotten, may be placed under the charge of the gardener. The traditions of the past have not merely to be maintained, but the gardeners of the present have to continue the forward march of improvement, by introducing better methods of cultivation wherever opportunity occurs, by improving the fruits, flowers, and vegetables already under cultivation, and originating new ones by the various means and methods at command. The field of enquiry is wide enough for every class of worker, and the practical cultivator may avail himself of the assistance at his disposal from various sources by acquiring a knowledge of the structure and nature of plants, just sufficient to enable him to comprehend the meaning of the information imparted by the more scientific worker.