KEY TO THE FAMILIES AND GENERA 



In one of the editions of the Cyclopedia of American Horticulture, a key to the families and genera 

 contained therein was placed in the introductory part to Vol. I. This key is now modified and adapted to the 

 present work. The original key was prepared by Wilhelm MiDer, Associate Editor of that Cyclopedia. The 

 main part of Dr. Miller's introduction to that key is here reprinted, with adaptations, as explaining the purpose 

 of a key and the way in which it is constituted. 



The key has now been extensively revised, but the original form and method are still retained. 



The purposes of the key. 



The following key attempts to supply what is proba- 

 bly the greatest deficiency in cyclopedic works on 

 horticulture: 



(1) It helps the gardener to determine the name of 

 any plant cultivated in America, including the wild 

 flowers and other plants native to the United States 

 and Canada that are commonly or even frequently 

 offered for sale. 



(2) It helps the student towards a scientific knowl- 

 edge of the plant world, since it gives a condensed 

 and orderly catalogue of that part of the vegetable 

 kingdom which is of interest to gardeners, farmers 

 and foresters. 



No merely alphabetical work can accomplish either 

 of these results. For example, suppose the person has 

 a flower that is known to be an Iris, but of what species 

 of Iris is not clear to him; and that he wishes to find 

 the name. If he were to consult the best works in which 

 the species of Iris are arranged alphabetically, it might 

 require hours to read the pages of description, com- 

 paring the items with the specimen, and the chances 

 are that in the end he would not be sure of a determi- 

 nation, since related species are not compared and 

 contrasted. 



It was to provide a short-cut to such information 

 that every large genus or group of plants described 

 in the Cyclopedia of American Horticultui-e was 

 classified according to shape, color, size, season, 

 height or other characters of interest to the gardener. 

 These short-cuts, or "keys," have long been in common 

 use with students of botany, and are a feature of all 

 floras, but they have not been sufficiently employed in 

 writings on horticultural .subjects. 



No valid objection can be made to keys, s}Tiopses 

 or other classified arrangements, since they do three 

 things more clearly and briefly than any other device: 

 (1) They help one to find out the name of a plant. (2) 

 They show the difference between the given species 

 and other species of the same genus. (3) They show 

 the relation of each species to every other, i. e., some 

 of the points of Ukeness and unlikeness. 



But classified schemes alone have one serious Umi- 

 tation: They are not so convenient for ready reference 

 if one knows one's plant and merely wishes to find out 

 the native country or how to spell the name. The 

 Cyclopedia of American Horticulture met this need by 

 numbering the species and providing an alphabetical 

 list or index in each large genus. It therefore met 

 the needs by presenting both systems — the classified 

 and the alphabetical — one for taxonomic study, the 

 other for convenience. 



All this supposes that one knows the genus to which 

 the plant belongs, — whether it is an Iris, Pa-onia or 

 Rhododendron. But he may not know the genus: the 

 key will aid him to determine it. The key leads to the 

 family and the genus; having the genus, he can run 

 down the species in the Cyclopedia itself, for the 

 genera are to be found in alphabetical order. This 

 key, therefore, deals only with families and genera, 



since the species are described and distinguished else- 

 where. It ties the whole work together and makes it 

 an organism, instead of a series of detached articles 

 on Iris, Rosa, Solanum, and other genera. In other 

 words, the key is not merely supplementary: it is 

 structural and even fundamental. 



The preparation of the key. 



It must be confessed, however, that the preparation 



of the key was undertaken with serious misgivings. 

 During the preparation of the Cyclopedia of American 

 Horticulture, the Editor was often importuned for 

 Something of the kind, by students, botanists, and 

 others who made increasing use of the volumes as 

 issued. In response to these urgent appeals, it was 

 necessary to point out three objections: (1) Such a 

 key would necessarily be highly technical. (2) It 

 would have to use a scheme of arrangement that may 

 pass with another generation. (3) The labor and ex- 

 pense would be great. 



In response to this demand the following key has 

 been prepared. It is based on the system of Bent ham 

 and Hooker as set forth in their "Genera Plantarum," 

 a work jsublished in parts from 1862 to 1883. The 

 system of Bentham and Hooker is not now the lat- 

 est, but it is the only one that was in general use 

 at the time the first Cyclopedia was begun. The 

 system of Engler and Prantl in "Die NatiirUchen 

 Pflanzenfamilien" is now well known; this no doubt 

 presents the best system for the present generation, 

 but in its turn it is likely to be superseded. In Engler 

 and Prantl's system the plants are arranged, as far 

 as possible, in the order in which the various fam- 

 ilies probably have made their appearance on the 

 earth's surface, or at all events in accordance with 

 the evolution from simple to complex. Perhaps the 

 new system is better adapted for showing relation- 

 ship or likeness, while the old system is well adapted 

 for bringing out differences. This furnishes an 

 additional reason for the use of the older system on 

 the present occasion, as most of those who use this 

 part of the Cyclopedia will probably be in search of 

 differences. 



In the present revision, the Bentham and Hooker 

 key-plan has been retained. The authors of the 

 main groups in the new Cyclopedia have made 

 revisions and adaptations to meet the changes and 

 requirements of their own work. New conceptions 

 of the limitations of families and genera have naturally 

 found expression in the revision. It is not designed to 

 insert in the key all the genera that are mentioned 

 in a minor or incidental way, for to include them all 

 would unnecessarily encumber and complicate the 

 lists and tend to make them unworkable; but it is 

 intended to include all the genera that afford species 

 prominently in the trade in the United States and 

 Canada. ' When it has seemed to be desirable to omit 

 genera from the key, the relatively unimportant 

 native groups have often been left out, for they may 

 be readily traced in the current botanies. 



(79) 



