xxu 



The Trees of Great Britain and Ireland 



invention of new names, except in one case for a species ' and in two or three cases 

 for hybrids," gives me a claim to be heard on the subject. In the earlier volumes, 

 I followed the Kew practice of the time, that of selecting as the correct name the 

 oldest one, which had been used under the genus to which the species is now 

 referred. In the latter volumes, I have followed, except in a few instances, the 

 Vienna Rule, that of adopting the oldest specific name, no matter to what genus 

 it had been attached. Most German and American botanists follow this rule 

 " blindly," as one of them remarked to me. 



As a result names which have been current for a century, not only in scientific 

 books but in popular literature, have now to give way to supposed earlier names, 

 which have been resuscitated from the works of writers whose descriptions are often 

 so ambiguous as to render it impossible to say what species was actually meant. 

 The strict application of the Vienna Rule is sometimes so difficult that the best 

 authorities disagree thereon. As an example, we are bidden to change the name 

 ,Alnus glutinosa, Gaertner, which has been used for the common alder for over a 

 century in every botanical text-book and Flora. Certain botanists substitute for it 

 the name Alnus rotundifolia, Miller, whilst one authority puts forth a strong claim 

 for Alnus vulgaris, Hill' This displacement of a well-known scientific name by an 

 obscure one is a pedantic and harmful practice. Its absurdity is shown by the fact 

 that some recent writers, who adopt under all circumstances the Vienna Rule, are 

 obliged, in order to specify clearly the species which they mean, to use two names, 

 the second of which is the old-established name in brackets. The common oak is 

 called by these writers^ " Quercus Robur, Linn. {Q. pedunculata)" \ while the wych 

 elm is cumbered^ with the appellation " Ulmus glabra, Huds. = U. montana." The 

 confusion of the new practice is doubled, when the Vienna name for a species 

 happens to be (as in the last case) the same as the old-established name for another 

 species of the same genus. Thus, no one now knows without some explanation 

 which species of elm is meant by the term Ulmus glabra. 



In order to avoid such confusion, I have preserved in certain cases the old- 

 established name, if its use involves no ambiguity. I have thus kept up Larix 

 europaa, Larix americana, Larix leptolepis, Abies pectinata, Quercus pedunculata, 

 Betula pubescens, Betula verrucosa, a series of names which have been consecrated 

 by long usage in books on botany, arboriculture, and forestry. If I am wrong in 

 using these names, I err in company with nearly all the writers who have mentioned 

 these trees during the last century. 



The postponement to the last volume of the more difficult genera has enabled 

 me to devote time, labour, and travel to their study ; and has resulted in a clearer 

 knowledge of the numerous cultivated kinds of elms and poplars, the systematic 

 position of which has been the despair of botanists. The results of the experimental 

 sowings of the seeds of various elms, which I made in 1909, together with a study 



Cf. Popubis MaxinKnviciii, vol. vii. 1 838. 



Cf. Populus Lloydii, vol. vii. 1 830, Ulmus Mossii, vol. vii. 1865, note 2. 



' Cf. Schneider, Laubhohkunde, ii. 890 (1912). 



* Cf. Schneider, Laubhohkunde, i. 197 (1904). 

 Cf. Tansley, British Vegetation, 148 (19H). 



