2 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY 
THE CLASSIFICATION OF GARDEN IRISES. 
I. Introduction. By W. R. Dykes, M.A., L.-es-L. 
This classification deals only with Bearded Irises * grown in gardens, 
and is based on comparative trials of the various varieties which were 
begun at Wisley in 191 5. At first it was hoped that it would be found 
possible to adopt a classification based on the wild species from which 
the various hybrids have sprung, but it soon became apparent that 
for garden purposes the colour of the flower and the height of the 
plant are of more importance than the botanical affinities of the 
latter, however interesting they may be in themselves. 
The plants are therefore arranged in colour groups, and against 
each plant in the list will be found the average height of the stem 
in inches and the approximate time of flowering. In this connexion 
it must always be remembered that the same plants grow very 
differently in different soils and environments, and that variations 
of temperature and moisture in different seasons have also consider- 
able influence on their growth. The measurements and dates given 
must therefore be understood to be relative rather than absolute, 
but it is hoped that the figures will show accurately whether one 
variety is taller or dwarfer than another, or flowers earlier or later. 
The adoption of colour as the basis of arrangement led at once 
to the vexed question of the names of colours. The segments of 
the flowers of an Iris are seldom uniform in colour when closely 
examined, and it is therefore hopeless to attempt to describe the 
colours by reference to any known colour chart. The colours given 
in the classification must be taken to represent the general effect 
of the various varieties as seen growing in the border at a distance 
of a few feet. A further difficulty lay in the fact that there is no 
general consensus of opinion as to the exact meaning of such colour 
names as violet, lavender, mauve, or lilac, all of which are frequently 
used in describing Iris flowers. It seemed best, therefore, to adopt 
the less definite names, " red-purple " and " blue-purple/' which 
could hardly be misleading, and merely to make subdivisions into 
" light " and " dark." 
It may be a disappointment to some gardeners to find that such 
botanical names as germanica, neglecta, plicata, squalens, etc., which 
have long been familiar in nurserymen's catalogues at the head of 
various groups of Irises, have now been abandoned. Increasing 
knowledge of Irises, as they are found growing in the wild state, has, 
however, shown that these names were originally applied to forms 
of the various hybrids and to 'sports to which the wild species do 
* It includes only the Pogoniris section of the genus, and excludes the 
Regelia and Oncocyclus sections, of which the flowers are also bearded. 
