PREFACE 



IN this edition the work is completely revised, and as far 

 as possible brought up to date. The most noteworthy 

 new feature is the incorporation of all the parts into one 

 general dictionary, and the omission of Part I of previous 

 editions. When first written this had certain advantages, as 

 being one of the few presentations in English of the ele- 

 mentary facts and theories of ecology. But this advantage 

 has long disappeared, and it seemed to me that the space 

 would be better employed in increasing the number of genera 

 dealt with. On consulting Sir David Prain and other bota- 

 nists, I found that they agreed with this idea. By a slight 

 addition to the total number of pages I have found it pos- 

 sible to include all the genera, and hope that in this way 

 the usefulness of the work to botanists in general may be 

 greatly increased. I have of course attempted no criticism 

 of those included, but have tried to indicate, as far as space 

 would permit, the genera from which they have been segre- 

 gated in many cases, or to which they are united by the 

 other of the two chief recent editors of the vegetable 

 kingdom (Bentham-Hooker, Engler-Prantl). It is obviously 

 impossible to do very much in this direction. As it stands, 

 the book is convenient for use, but a very slight addition 

 to the facts given for each genus would add a line to the 

 entry and, as there are roughly some 20,000 entries, this 

 would add 400 pages to the book, and make it unwieldy. 

 The same remark applies to the geographical distribution, 

 which could not in general be given in great detail. 



Before criticising, again, the inclusion of many obsolete 

 technical terms and synonyms, it must be remembered that 



o I 



