VOL. I. INTRODUCTION. vii 



supply a work adapted to general circulation and use. On the other hand, it was found that 

 any considerable further reduction of the figures in order to reduce the size of the work, 

 would be at the sacrifice of the clearness and usefulness of the illustrations. 



In the general plan adopted and in giving parts only of the larger plants, it has been the 

 constant aim to make the reduction of each figure as little below life-size as possible, to 

 select the most characteristic parts for illustration and to preserve the natural proportion. 

 In these respects, it is believed, the present work will be found to be at least not inferior to 

 that above named and often superior. 



The cuts are all from original drawings for this work, ether from life or from herbarium 

 specimens, though reference has constantly been ma.de to published plates and figures. All 

 have been first drawn life-size from medium-sized specimens, and afterwards reduced to the 

 proportion indicated by the fraction near the bottom of each 'cut, most of them being from 

 $ to of medium life-size. By this method the illustrations do not suffer from the use of a 

 magnifier, but are improved by it and retain their full expression. 



The large number of additional figures in the second edition and the incorporation into 

 the main text of the appendix to the first edition, have necessitated the renumbering of the 

 figures consecutively. 



Enlargements of special parts are added in most of the illustrations in order to show 

 more clearly the floral structure, or minute organs, or the smaller flowers. These are in 

 various degrees of enlargement, not deemed necessary to be stated. The figures are 

 uncolored, because coloring, except in costly work, obscures the fineness of linear definition 

 and injures the cuts for descriptive and educational uses. 



The Classification of Plants. 



The Plant Kingdom is composed of four subkingdoms, divisions or primary groups : 



1. Thallophyta, the Algae, Fungi and Lichens. 



2. Bryophyta, the Mosses and Moss-allies. 



3. Pteridophyta, the Ferns and Fern-allies. 



4. Spermatophyta, the Seed-bearing plants. 



Individuals are grouped, by similarity, into races ; races into species ; species into genera ; 

 genera into families; families into orders; orders into classes; classes into divisions or 

 subkingdoms. 



In addition to these main ranks, subordinate ones are sometimes employed, when closer 

 grouping is desirable : thus a Class may be separated into Subclasses, as the Class Angio- 

 spermae into the Sublasses Monocotyledones and Dicotyledones ; Families may be separated 

 into Tribes, as in the treatment of Gramineae in the following pages; Genera are often sepa- 

 rated into Subgenera; Species into Subspecies. 



Critical field observations of plants in the wild state, supplemented by the cultivation 

 side by side of species supposed to be distinct and by the lessons learned from experimental 

 plant breeding, have developed the theory that many species, perhaps all, are composed of a 

 greater or lesser number of races, differing from each other too little to cause them to be 

 regarded as species, notwithstanding the fact that they may breed true from seed to such 

 slight or trivial differentiations. It also seems to have been proved, by DeVries and others, 

 that such differentiations may originate abruptly from seed, in a single generation, and remain 

 constant for at least several generations thereafter if. so isolated from their relatives as to 

 prevent cross-pollination. These recently ascertained phenomena of mutation are most sug- 

 gestive, 1 and experimentation and observation concerning them are now occupying the atten- 

 tion of many students. 



In the present edition of " Illustrated Flora," the view is taken that the races composing 

 many species are often too numerous and too slightly characterized to be described so as 

 to be recognized ; many of them have been described as species and many more as varieties, 

 and varieties of different degrees of differentation have been suggested. We here regard 

 species alone as entitled to distinct botanical appelation ; it has been suggested that races may 

 be indicated numerically. 



Other than the omission of descriptions of varieties, the general system of classification 

 used in the first edition has been maintained in the second. A few new family groups and 

 a number of genera have been separated or distinguished from their congeners. 



