390 PLANTS, SEEDS AND CURRENTS 



neutral attitude in the matter he adopted the implication as regards 

 alien plants. He considered that all " recorded constituents " of 

 the Azorean flora should be taken into our " statistical reckonings " 

 (p. 264), and he made a numerical analysis (p. 272) without any- 

 further differentiation than one based on geographical considerations. 

 The results were used by Godman, with no comment on the pre- 

 dominant proportion of alien plants, in his concluding general remarks 

 on the natural history of the islands (pp. 332, 334), and, as is noted 

 below, by other writers on insular floras. 



The effect has been unfortunate, since these writers have treated 

 Watson's catalogue of 439 plants as a list of native plants. He him- 

 self remarks (p. 262) that his catalogue includes many species that 

 have been introduced into the Azores ; but evidently it did not fall 

 within the scope of his work, as he viewed it, to discriminate to any 

 extent between the natives and the aliens among the plants. To 

 take one instance, Watson's list includes about two dozen species 

 in all of Medicago, Trifolium, and Lotus, of which the majority must 

 have been introduced since the discovery of the islands; yet there 

 is nothing to indicate it. Then again, of the fifty-one grasses named 

 he only particularises three as possibly introduced. So also of the 

 six species of Geranium and Erodium, almost all of them common 

 ruderal species, of the sixteen species of Labiatce, which include many 

 roadside and waste plants spread by cultivation, and of such familiar 

 world-ranging weeds as Oxalis corniculata, Plantago major, P. lanceo- 

 lata, Rumex crispus, etc., nothing is said of their alien origin. 



The outcome of this will now be shown. When Godman in his 

 book on the group (p. 342) compared the proportion of peculiar 

 Azorean plants with those for birds, insects, and land-molluscs, 

 he was employing Watson's entire list of plants as though all were 

 natives of the islands. Then again there was little in Watson's 

 work to guide Wallace in discriminating between native and foreign 

 flowering plants, when he made an analysis in his Island Life of the 

 439 Azorean species based on their capacity for dispersal. Yet 

 he was fully sensible of the difficulty involved. " There can be " 

 (he writes, edit. 1892, p. 260) " little doubt that the truly indigenous 

 flora of the islands is far more scanty than the number of plants 

 recorded would imply, because a large but unknown proportion of 

 the species are certainly importations, voluntarily or involuntarily, 

 by man. ... It is almost impossible now to separate them, and Mr. 

 Watson has not attempted to do so." He goes on to say that even 

 if only half of the species are truly indigenous there would remain 

 a wonderfully rich and varied flora to have been carried by the 

 various means of dispersal. But apart from this, the danger of 

 treating all the plants in Watson's list as native plants has not always 

 been avoided. Thus, in comparing the endemic element in insular 

 floras, Watson's total for the Azores has been sometimes utilised as 

 if it were composed entirely of native plants. This is the case in 

 a list given in the Introduction to the Botany of the Challenger Expedition 

 (p. 33). Then again in works of reference the same thing is done. 

 Thus in the article on the Azores in the 9th edition of the Encyclo- 

 paedia Britannica, which was written before 1875, all the 478 flowering 

 plants, ferns, and lycopods, etc., of Watson's list are characterised 



