On the Origin and Distribution of the British Flora. 77
and doubtful species, we may well adopt Forbes's title of
Germanic, which applies to 1059 out of 1425 British species,
since their extension into Scotland, or their exclusive occur-
rence in the higher latitudes of that country, are questions
of secondary importance as compared with their continental
distribution. For the Highland type, including 120 species,
we may use the more general term of Arctic-Alpine, retain-
ing the names Asturian and Armorican for two other types or
subfloras.26 With the exception of two or three waifs from
America,27 the whole British flora occurs on the Continent of
Europe, as we might expect, considering the recent geological
date of the separation of our islands. Though, however, the
time which has elapsed since this separation has not been
sufficient for local forms of specific importance to originate,
it is quite possible that a minute study of what are known to
botanists as critical species, such as the aquatic Ranunculi,
the brambles, roses, hawkweeds, and willows, may disclose
varieties that are not only peculiar to the British Islands, but
to particular districts.28 If then we wish to investigate the
distribution of plants within the limits of Great Britain, we
26 The revised classification will therefore be as follows :—
Germanic (1186):— Species.
British....... 532
English (including Forbes's Kentish) . 536
Intermediate . . . . . . 37
Scottish....... 81
Arctic-Alpine ...... 120
Armorican ....... 59
Asturian ....... 11
Doubtful....... 49
Total No. of species on Watson's estimate . . 1425
27 These are Eriocaulon septangulare, a North American species found
in Skye, the Hebrides, and from Antrim to Connemara ; and Spiranthes
gemmipara, also a United States plant, which occurs in County Cork.
28 No doubt the closer comparison of English critical forms with those
of the Continent will prove that many, if not all, occur in both districts ;
still it can hardly be doubted that the distribution-areas of segregates will
prove more limited than those of aggregates. This line of inquiry, which
requires considerable acumen, is as yet almost untouched.