EXPLANATORY INTRODUCTION 



The Index of English names, technical terms, &c., which formed 

 Part III of former editions, is now incorporated with the list of 

 genera, so that the work forms one dictionary from end to end, with 

 the exception of the key to the families at the end of the book. 



All the genera of Bentham- Hooker, Engler-Prantl, and Linnaeus 

 are now included, as well as all given in the Index Kewensis and 

 Supplements (except many synonyms), together with a large number 

 published since the last Supplement, and which, by the kindness of the 

 Director of Ke\v, I have been able to obtain from the MS lists kept 

 at Kew. The most recent of these are given in a little Supplement at 

 the end of the main dictionary, and I hope to bring this supplement 

 up to date at intervals during the currency of the edition, adding 

 the entries later to the body of the work so far as the padding will 

 allow. Besides the genera, all families and higher divisions are also 

 included. 



The name of the genus is followed by the name of its author, often 

 abbreviated, e.g. R.Br. (cf. Abbreviations), on the system explained 

 under Nomenclature. The original description of the genus may be 

 found by reference to the Index Kewensis. In the same way, the 

 author is given after every species quoted, and the original description 

 may be discovered from the same book. 



Owing to the continual changes that go on in many families and 

 genera, names are often reduced to synonyms; a great number of such 

 are given in this book, chiefly those used in well-known floras; e.g. 

 Abildgaardia Vahl = Fimbristylis Vahl. Under some of the best known 

 genera, e.g. Abies, a few specific synonyms have also been given, 

 especially names frequently met with in gardens, and opposite to each 

 of these is given the name now generally used; thus Abies alba Michx. 

 must be looked for under Picea, Abies Douglasii Lindl. under Pseudo- 

 tsuga, and so on. It is very difficult to decide when divergence of two 

 forms is sufficient to entitle them to rank as genera, and this difficulty is 

 the cause of much synonymy. A genus A is established by one author, 

 and then it is discovered not to differ sufficiently from another genus/?, 

 established by the same or another author, to remain as an independent 

 genus. A is therefore merged in B and becomes a synonym. The 



