[5]See Bostock’s translation of Pliny, vol. iii. p. 194, &c.
APPENDIX E.
On the Canarian Flora as compared with the Maroccan.
By Joseph Dalton Hooker.
In respect of their botanical relationship to neighbouring Continents, Islands or Archipelagos may be roughly classed under two divisions: namely, those which are situated within a moderate distance of continents, and whose Floras are manifestly derived from them or have had a common origin with theirs; and those which are situated very far from any continents, and whose Floras differ so much either from that of the neighbouring continent or from that of those parts of the continent that are nearest to them, that their origin is a matter of speculation. Of the first division, the British Isles, and probably Vancouver’s Island, in North-West America, are conspicuous instances, their Floras being almost identical with those of the neighbouring continents. St. Helena, the Galapagos, Mauritius, and the Sandwich Islands are instances of the opposite extreme, for their Floras differ widely from those of any continents.
Between these extreme cases there are many intermediate ones; and there are others of an exceptional character, as Iceland, which, though far removed from any part of Europe, has but one flowering plant not found on that continent (Platanthera hyperborea); and Ceylon, which though it is almost united to the Peninsula of Hindostan, yet in many respects differs greatly from that peninsula in its Flora.
Amongst the exceptional cases to continental proximity being accompanied by close botanical relationship is the Flora of the Canarian Archipelago, which differs so greatly from that of the northern part of its neighbouring continent, namely, from that of Marocco,[1] that it demands notice in any work treating of the vegetation of the latter country.
This diversity between the Maroccan and Canarian Floras has been pointed out in Ball’s ‘Introductory Observations to the Spicilegium Floræ Maroccanæ,’[2] where it appears that whilst Marocco, out of 1,627 species of flowering plants, contains 165 endemic plants, it has only 15 which are confined to it and to the Canaries, or to it and Madeira. And Ball goes on to remark (p. 301), in respect of these few species common to both Floras: ‘I think it is safe to say that the facts rather tend to show the accidental diffusion of a few Macaronesian[3] species on the adjacent coast of Africa, than to indicate the direct connection between the continent and those islands within a geological period at all recent.’
Were this diversity due solely or chiefly to the Canaries wanting many Maroccan plants, the inquiry would not be a pressing one; but as to this deficiency is to be added the presence in the Canaries of many indigenous species, and even several genera[4] which are absent in Marocco, and in Marocco the great rarity of endemic genera, of which Argania only is arboreous, the inquiry becomes a very important one, inviting a much closer study than can here be given to it.