INTRODUCTION 
This book is the result of an attempt to find plants that would flower in the open in the winter 
months in Surrey. The fascination of the first Iris flowers that were obtained led to an interest in the 
whole genus, and it soon became apparent that our knowledge of it was very defective. 
In the attempt to remedy this defect, I have refused as far as possible to take anything for 
granted and have therefore made little use of the various Floras of different districts and regions because 
investigations into the original descriptions of the various species and acquaintance with the plants 
commonly cultivated under these names proved that there was very great confusion in Iris nomenclature 
and that it was accordingly impossible to rely on the statements in local Floras to the effect that certain 
species of Iris were natives of certain districts. 
The method that appeared most likely to give satisfactory results was first of all to go back to the 
original descriptions of all the supposed species of Iris, amounting to some seven hundred, and to 
endeavour, with the help of the type specimens, wherever these were available, to arrive at some 
conclusion as to which of the names were worthy of specific rank and which were to be regarded merely 
as synonyms. 
This puzzling and somewhat tedious task was carried out for the most part in the excellent botanical 
library of the Kew Herbarium, and I owe a great debt of gratitude to the officials there and especially 
to Dr Stapf, the Keeper, and to Mr Skan, the Librarian, for their never-failing courtesy and ready help. 
The former gave me invaluable hints as to method and without the extensive bibliographical knowledge 
of the latter my search for various obscure references would often have been fruitless. 
When I had thus arrived at some idea of the various species, I proceeded to check it by working 
through all the available herbarium material, which at the same time provided me with details as to the 
distribution of each species. In arranging my information under the heading of "Distribution," it seemed 
better to be able to vouch personally for each entry, and I have therefore quoted no specimens that 
I have not examined myself. Since in nearly every case the date and the collector’s name are given 
as well as the indication of the collection in which the specimen is now to be found, it is hoped that 
there will be no difficulty in determining what plant I take to be meant by any specific name. 
This method has doubtless the drawback that the full extent of the distribution may not always 
be indicated, but there is perhaps some compensation for this defect in the fact that the errors of local 
Floras are not perpetuated. The collections examined include those at Kew, in the British Museum 
(Natural History Branch, South Kensington), at Oxford, Cambridge, Edinburgh, at the Berlin Botanic 
Garden, and at the Vienna Hofmuseum. In addition, I have examined a number of specimens from the 
Jardin des Plantes at Paris, from the United States National Museum at Washington, D.C., from 
M. L^veiMs collection of Chinese plants at Le Mans, a small collection of Italian specimens belonging 
to Prof. Terracciano and part of the collection of the Imperial Botanic Garden at St Petersburg. 
The letter in brackets after each specimen quoted indicates the collection in which the specimen 
is to be found. The following are the abbreviations used. 
K Kew Herbarium. 
BM British Museum, Natural History Branch at South Kensington. 
O Oxford University Herbarium. 
C Cambridge University Herbarium. 
E The Herbarium of the Edinburgh Botanic Garden. 
B The Herbarium of the Berlin Botanic Garden. 
P The Herbarium of the Jardin des Plantes at Paris. 
V The Herbarium of the Vienna Hofmuseum. 
SP The Herbarium of the Imperial Botanic Garden at St Petersburg. 
L M. L£veill£'s Chinese plants at Le Mans. 
VV The Herbarium of the United States National Museum at Washington, D.C. 
T A collection, chiefly of Italian specimens, lent to me by Prof. Terracciano. 
HortD Indicates that the plant is, or was, in cultivation in my garden, and in most cases that it came 
to me direct from the locality named. 
If there is one point more than another that has come into prominence in the course of this work, 
it is the endless confusion that arises from the fact that new plants are described without reference to 
the most closely allied, previously known species of the same genus Thus Max.mow.cz m describing 
his I Bungei is careful only to distinguish it from /. songanca Schrenk, w.th which no one would easily 
confuse it; moreover, conveniently for himself, and inconveniently for us, he omits any mention of 
/. tenui/olia Pallas from some specimens of which it is much more difficult to distinguish 1 . 
D. 
