THE AZORES 



391 



as " generally considered as indigenous." Yet Watson's attitude 

 reflected the prevailing opinion among botanists in this matter. 

 Hooker, in his famous lecture on Insular Floras in 1866, a lecture 

 which has formed the foundation of all later studies of these floras,, 

 would almost seem to imply that the 350 species of flowering plants, 

 then known were all natives. 



It is not easy for us now to grasp the pre-Darwinian conception 

 current in the middle of last century. It was the period of change 

 between two eras, and it was left to Trelease in recent years to 

 recognise the limited character of the true native flora of this group.. 

 The flowering plants designated by him as introduced since the 

 occupation of the islands, including weeds, escapes, casuals, etc., 

 number in all nearly 200 ; but even Trelease omits to mark as alien 

 to the native flora a considerable number of species, such as Lamium 

 purpureum, Stachys arvensis, Oxalis corniculata, Geranium molle? 

 G. robertianum, G. dissectum, Galium aparine, etc., amounting pro- 

 bably to almost another hundred, which must be regarded as having 

 been introduced since the discovery of the archipelago. 



One way of testing this matter, as suggested to me by Mr. Hemsley, 

 is to take the case of the New Zealand flora, where the introduced 

 plants have been carefully discriminated by Cheeseman. This, 

 however, would probably develop into a much larger undertaking 

 than I could begin now, since numbers of collateral questions would 

 arise, and the area of comparison would certainly require to be greatly 

 extended as the inquiry proceeded. Unless some abler worker takes 

 up the subject, I hope to begin the task some day. It would be 

 important to eliminate the agency of man, direct and indirect, 

 from every flora, and to apply the same method to all. Such an 

 inquiry might be almost as ruthless in its effects on the British flora,, 

 as it would undoubtedly be in the case of that of the Azores. As 

 applied to the group just named, the term " native flora " denotes 

 the plants in the islands before their occupation by man. It has 

 in practice a widely different meaning in the case of the British 

 Isles, and includes a host of ruderal plants. Yet if a weed had been 

 present here for half a million years, it would still be a weed and never 

 a part of the native flora. 



Whatever the antiquity of the weed, its differentiation from the 

 native plants of a flora, or, in other words, the disentanglement of man's 

 influence in the history of the plant- world, becomes the first requisite 

 for the proper study of distribution. Whether a region was first 

 occupied by man 400 or 400,000 years ago matters little. The weed 

 of to-day is the weed of prehistoric ages, and its story is bound up 

 with the story of man on this globe. Results, both unexpected and 

 important, would be the outcome of such an investigation. 



Probable Composition and General Characters of the 

 Original Forests of the Azores. — Although he did not see his 

 way to assist us in the differentiation of the weeds, Watson (p. 268) 

 gives some valuable suggestions that enable us to form a mental 

 picture of most of the general characters of the dense woods that 

 covered these islands at the time of their discovery. We may here 

 emphasise his opinion that evergreen shrubs and trees, with ferns 

 and mosses, formed the principal feature of the vegetation, and that 



