Introduction. 5 
forms, of which we found several, each occupying well- 
defined small areas, and apparently possessing definite 
characters. But, as more and more of the patches were 
examined, these distinctions were found to melt away ; for 
each fresh patch yielded a slightly different form, so that 
finally we were able to obtain a nearly complete series of 
intermediates seeming to connect the extreme S. umbrosa 
with the extreme S. Gewzz, all of them living within a 
small area under similar conditions. Pinguicula vulgaris 
and P. grandifiora, on the other hand, we found growing 
together in abundance, and quite distinct except at one 
spot where, below a rock on which both grew, we found a 
number of hybrids. In this case the allied forms, some- 
times only ranked as sub-species, are both good species, and 
have different geographical distributions, though they over- 
lap at more than one point. Botanical books are full of 
similar anomalies, often due to a natural desire to announce 
the discovery of a form new to Britain ; but for the student 
of geographical distribution varietal names founded on 
such material are worse than useless. For they tend to 
confound sub-species, which, if found in isolated areas show, 
in all probability, a transportation of the seeds from one 
to another, with varieties or forms, which will reappear 
wherever the parent species is subject to particular con- 
ditions. 
A flora like that of the British Islands may be studied 
in so many different ways, that it will be well to define at 
once the standpoints from which it is viewed in the following 
pages. I do not propose, nor do I feel competent, to 
touch on the questions of the evolution of the species, or 
of their relationship to each other ; what will be attempted 
in Chapter IT. is, to give a sketch of the existing flora as 
a whole, to note its composition, and the distribution of 
the species. Chapter III. will deal with the means of 
