viii PREFACE 



forcing of vegetables. We now think in terms of cropping under glass. The range of 

 species of plants involved in these industries is relatively small, but the areas are large, 

 the business is receiving the attention of able men and women, and the glasshouse 

 industries are making important contributions to the lives of the people. The recent 

 growth of the commercial fruit-growing industry is also notable. Once largely restricted 

 to narrow regions and to "fruit belts," the growing of fruits for market has now 

 assumed the proportions of a great industry comparable with the staple agricultural 

 productions. An effort has been made to catch something of the spirit of all these 

 large efforts, as well as to provide information and advice for the amateur and the 

 home gardener. 



When the Cyclopedia of American Horticulture was made, there were few special- 

 ists in the systematic botany of cultivated plants. The Editor hopes that the publica- 

 tion of that Cyclopedia has contributed something to the acceleration of interest in this 

 long-overlooked subject. Howbeit, the number of competent specialists, and of 

 those intelligently interested in the subject, is now large enough to have enabled the 

 Editor to cover many of the important groups. The cacti have been placed mostly in 

 the hands of J. N. Rose; a number of tropical plants have been handled anew by 

 W. E. Safford; the orchids, aroids and bromeliads by George V. Nash; euphorbiads 

 by J. B. S. Norton; Citrus and related genera by Walter T. Swingle; Nymphseacese by 

 H. S. Conard; the ferns by R. C. Benedict; most grasses by A. S. Hitchcock; special 

 groups by Norman Taylor, chiefly among the composites, palms, and tender araliads; 

 suggestions on cultivated forms and on cultivation have been contributed by C. P. 

 Raffill, of the tropical department, Kew; the survey of families of plants and most 

 of the editorial work on the general introductory key have been in the hands of 

 K. M. Wiegand; and many small groups and special genera have found new treatment 

 by persons who have given them careful study over a considerable period of time. 

 The results of modern scientific studies are now beginning to be positively reflected in 

 the identification of garden plants, and in the advice for the cultivation and handling 

 of horticultural crops and products. With so many persons partaking, it is of course 

 impossible to secure uniformity of taxonomic handling in the various groups, but the 

 gain of having the contributions of specialists will abundantly offset this small 

 technical disadvantage. 



And yet, it is true that very much of the work is necessarily compiled from litera- 

 ture rather than constructed from a direct study of the plants themselves. There is no 

 herbarium or other complete and authentic repository of all the species of plants sold by 

 dealers. The best that can be done in very many cases is to accept the name appearing 

 in a catalogue and to attach to it the most authentic or most adaptable description of 

 a recognized botanical species of the same name; there is no telling whether the dealers' 

 plant is properly determined or whether it represents the botanical species bearing the 

 same name. It is impossible now to know how many wrong determinations, inaccurate 



