BOTANICAL SOCIETY OF LONDON. 
7 
Of the multitude of species growing in all parts of the 
earth, and forming what is commonly termed the vegetable 
kingdom, only a very small number in proportion to the 
whole, can be collected in any particular district or country. 
But the amount of species in any one county, or National 
Flora, constitutes a great proportion of other Floras, whether 
provincial or territorial, especially of such as are in conti- 
guous regions. The number of vascular species, sponta- 
neously growing within twenty-five or thirty miles of Lon- 
don, equal in amount two-thirds of British plants of the 
same kind. They are more than double of the number in 
the Flora Lapponnica. They exceed the number in Sweden ; 
form one-half of the German Flora; rather above one-third 
of the Austrian Flora ; and about one-fourth of the French 
Flora. 
As all these countries, with the exception of part of Swe- 
den, the whole of Lapland, and the South of France, lie in 
the same parallels of Latitude, the species found in any one 
of them will generally constitute part of the species of the 
others. For example, most of the Lapland plants are natives 
of Sweden. The greater part of the Swedish plants will be 
found in Germany. The German plants again constitute a 
large portion of the Floras of Austria and France. Nearly 
all our British plants grow in these continental kingdoms, 
with considerable additions of species, genera, and even fa- 
milies. Our insular situation has formed a barrier to the 
migration of many European species and genera, although 
our climate be suitable for their preservation and propa- 
gation. 
If we compare our Flora with Intra-Tropical Floras, we 
shall perceive an immense decrease in the number of common 
species. A section of the Peninsula of Hindustan, extending 
from Lat. 9° to 19° north, according to Wight and Arnott 
produces two thousand eight hundred Phaenogamous species, 
of which not above thirty are natives of this country. In 
the Western Hemisphere, the Tropical Flora of America, by 
Humboldt and Bonpland, comprises six thousand species of 
which not one Dicotyledonous plant is found even in Europe, 
and only a very few of the Monocotyledonous species. 
Receding from the Equator in both Hemispheres, the pro- 
portion increases. The North American Flora contains four 
hundred European species, and the Flora of New Holland 
or New South Wales one hundred. These facts prove that 
