INTRODUCTION 
xv 
Retention of Linnaean trivials 
A very important nomenclatorial matter arises in cases where an aggregate species is sub- 
divided into two or more species. Thus, when Crataegus oxyacantha is subdivided into two 
species, shall the old specific name be rejected altogether or retained for one of the smaller 
species ? Here again the practice among botanists varies ; and often the same botanist will 
sometimes adopt the one plan and sometimes the other. By Article 44 of the international rules, “a 
change of characters, or a revision which involves the exclusion of certain elements of a group 
or the addition of new elements, does not warrant a change in the name or names of a group,” 
except in certain specified cases. These specified cases refer chiefly to names which are invalid 
on other grounds, and to the case when the group designated by the name in question “embraces 
elements altogether incoherent, or when it becomes a permanent source of confusion or error ” 
(Art. 51, 5). Though there is here a certain amount of opportunity for differences of opinion, 
it is clear that the intention of the framers of the rule is that the older aggregate names should 
be retained wherever possible, and that the prerogative of rejecting the older aggregate names 
should be exercised on as few occasions as possible. We interpret the rule in question in this 
spirit, retaining the earliest trivial name whenever the plan seems desirable : there are occasions, 
however, when the retention of the earliest trivial name leads to so much confusion that it is better 
to reject it. 
The use of capitals for trivial names 
With regard to the use of small or capital letters for trivial names, there is no precise rule 
or custom among botanists. It is the practice of most botanists to begin some trivial names 
with small letters and others with capital letters ; but here all appearance of agreement ends. 
Some botanists use capitals for trivial names when they commemorate a place or person or 
a pre- Linnaean genus. Others use capitals only for trivial names which commemorate places 
or persons. A recommendation by the international congress is that trivial names should begin 
with small letters except those which are taken from names of persons or from generic names. 
There are also other plans in actual use ; but we know of no work in which any one plan 
is quite consistently followed. There are so many difficult cases that it is not surprising that 
even the most careful authors make many slips. 
In our opinion, there are only two .-plans which can be said to be logical or which can be 
consistently applied. One is to spell all trivial names with initial capital letters, as was done by 
some of the older botanists, e.g., Miller. The second is to spell all trivial names with initial 
small letters ; and this is the plan adopted in the present work. The adoption of this plan is 
no innovation, as it has long been in general use among zoologists ; and it is also adopted by 
many geologists and by some botanists. It is obviously desirable that biologists should have 
a uniform plan ; and the only hope of obtaining this seems to be in adopting the plan which has 
so long been used by zoologists. 
Use of Linnaean symbols in trivial names 
In the Species Plantarum, Linnaeus has sometimes added a symbol after a specific name. 
For example, Linnaeus writes “ Scandix pecten $” and “ Veronica anagallis V-” According to 
the commentator of the international rules (Art. 26, annot.), these symbols must be transcribed ; 
and the specific names in question then become Scandix pecten-veneris and Veronica anagallis- 
aquatica. We cannot see that this is demanded by Article 26 of the rules ; and as the resulting 
trivial names are not only clumsy but sometimes misleading, we do not adopt them in the 
present work. We write merely Scandix pecten and Veronica anagallis. 
Varietal names 
The rule for the names of groups of plants of lower than specific rank in no way differs 
from the general rule already laid down (see p. xi). Hence, when a variety of a species has once 
been named, it is not possible to change its varietal name, so long as the plant retains varietal 
rank, even if the variety is afterwards referred to another species ; and the same principle 
applies to subspecies, subvarieties, formae, and (if these be recognised) races. Much confusion 
has been caused through the non-observance of this rule, more particularly perhaps in this 
country. There has been a practice here (a practice, however, inconsistently followed), of retaining 
