406 APPENDIX E. 



■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. 



The Flora of the Canarian Archipelago, though consisting, 

 like the Maroccan, for the most part of Mediterranean species, 

 yet differs from that of Marocco, iq containing many plants 

 that may be classed under the following categories : — 



I. It contains many non-Maroccan plants, obviously intro- 

 duced by man, and not from Europe only, but from various 

 parts of both the Old and New "Worlds. This will not appear 

 surprising when it is remembered that Teneriffe was for several 

 centuries the Prime Meridian of Geographers and the resort of 

 all the European ocean-navigators, who took their departure 

 from it on their outward voyages, and made for it on their home- 

 ward ones. The Alternanthera achyrantha, a tropical American 

 plant, was no doubt imported into the Canaries, and possibly 

 from thence introduced into Spain (where it is now natural- 

 ised). Argemone mexicana is another, and there are still other 

 as conspicuous examples of such foreign introductions. This 

 maritime intercourse can, however, only partially account for 

 the remarkable disproportion between the number of probably 

 introduced plants in the Canaries and in Marocco; and we 

 must take into account the isolation, barbarism, and exclusive- 

 ness of the latter country, and the absence of any commercial 

 intercourse between it and the Canaries or the rest of the world. 



In Webb and Berthelot's ' Phytographia Canariensis ' up- 

 wards of fifty plants are enumerated as to which we have little 

 doubt that all liave been introduced by man, and none of which 

 have hitherto been found in Marocco. The list includes many 

 weeds of the widest tropical and temperate distribution, as spe- 

 cies of Sida, Waltheria, Siegesbeokia, Bidens, Lippia, Physalis, 

 Nicandra, Euphorbia, Alternanthera, Gommelyna, and various 

 CyperacecB and Grasses. 



II. The Canaries contain many apparently indigenous 

 plants, which, though not Maroccan, are widely distributed 

 elsewhere; these form a large class, and the following are 

 some of the most prominent of them ; — 



Canarina, Mussohia, Bosea, and Gesnomnia. The only endemic genera 

 in Marocco are Argania, Hemicrambe, Ceratoonemum; and Sclerosciadium. 



