Page:VCH Norfolk 1.djvu/73

BOTANY R. Leathes, the brothers C. J, and Sir James Paget, B. Bray (of Lynn), and the Rev. Kirby Trimmer, and in his own special subject, Diatoms, Frederic Kitton. Division of the county for Botanical Purposes. — Unfortunately the watersheds of Norfolk do not lend themselves to any system of division, and whatever system is adopted will be of necessity purely artificial. Mr. Hewett Cottrell Watson in his Topographical Botany took the first degree of longitude east of Greenwich as the division between east and west Norfolk, his vice-counties, Nos. 27 and 28 : this line, which enters from the north at Blakeney (approximately) and leaves the county at Lopham to the south, divides it into two fairly equal portions, but this division is hardly adequate to show rarity or frequency of the occurrence of species within the county itself, however useful it may be for comparison with the rest of Great Britain. In 1864 the Rev. G. Munford in the article ' Botany,' which he wrote for the 3rd edition of White's History of Norfolk, first proposed a division into four portions, which was adopted by the Norfolk and Norwich Naturalists' Society at their first meeting on April 27th, 1869, and has since been used for the society's lists of local flora, which may be described as follows : On the map of Norfolk draw two perpen- dicular lines, one running through Norwich and the other through SwafFham, and connect them by a horizontal line between those two places. This divides the county into two fairly equal central portions, having the division containing the ' Broads ' to the east and that contain- ing the ' Fens ' to the west, and these divisions are called eastern, ' -E ' ; north-central, ' ivc ' ; south- central, *■ sc^ ; and western, '^' These divisions have been indicated by their initial letters for the purposes of the present article. Taking the ninth edition of the London Catalogue for our guide we find that the Flora of Great Britain, Ireland, and the Channel Islands contains 1,958 numbered items which we must call ' species,' and if we exclude the genus Rubus, concerning which so much difference of opinion and uncertainty exists and which numbers 99, we shall have 1,859 to be accounted for. Of these 1,164 have been recorded as occurring in the county on fairly good authority, and further, if we consider that the genus Hieracium, which numbers in the Catalogue 100 species, counts with us for only 5, we find that of the remainder of the species of the whole kingdom we have reason to claim just about two- thirds as having been found within the limits of the county. It must not be supposed that all the species counted are native or indigenous. 96 of them are printed in the Catalogue in italics as having no claim to be so regarded, and of the remainder many others belong to the classes which Mr. H. C. Watson described as ' denizen,' ' colonist,' or ' alien,' and a few are ' casuals,' but how readily a ' casual ' or an ' alien ' may become a well-established ' colonist ' or ' denizen,' presenting the appear- ance at first sight of a ' native,' is shown by the instance of Veronica Tournefortii, which first noticed about 1830 has in seventy years become 41