PRESIDENTIAL ADDRESS. 771 



boon to others as well as to students were a full synonymic list prepared to show 

 clearly the equivalence of the names where those for the same species or variety 

 differ in the different lists and manuals. Probably in time an agreement will be 

 generally arrived at regarding the names to be accepted, but that desirable con- 

 summation seems hardly yet in sight. Meantime the most useful step seems to 

 be to show in how far there is agreement in fact under the different names. 



Among the Cryptogams certain groups have fared better than the higher 

 plants as regards both their later treatment and their more adequate illustration 

 by modern methods and standards. Several works of great value have dealt with 

 the mosses, the latest being Braithwaite's ' British Moss-flora,' completed in 1899. 

 The Sphagna were also treated by Braithwaite in 1880, and are to be the subject 

 of a monograph in the Eay Society's series. The liverworts have been the subject 

 also of several monographs, of which Pearson's is the fullest. 



Among the Thallophyta certain groups have been more satisfactorily treated 

 than others — e.g. the Discomycetes, the Ureclinea3 and UstilagincEe, the Myxomy- 

 cetes, and certain others among the fungi, and the Desmidiacere among the algse ; 

 but the Thallophyta as a whole are much in need of thorough revision to place 

 them on a footing either satisfactory or comparable to their treatment in other 

 countries. 



Of the Thallophyta many more of the smaller species will probably be dis- 

 covered within our islands when close search is made, if we may judge by the 

 much more numerous forms already recorded in certain groups abroad, and 

 which almost certainly exist here also ; but among the higher plants it is not 

 likely that many additional species will be discovered as native, yet even among, 

 these some will probably be found. It is, however, rather in the direction of 

 fuller investigation of the distribution and tendencies to variation within our 

 islands that results of interest are likely to be obtained. 



The labours of H. C. Watson gave a very great stimulus to the study of the 

 distribution of the flora in England and Scotland, and the work he set on foot has 

 been taken up and much extended by numerous botanists in all parts of the 

 British Islands. It is largely owing to such work and to the critical study of the 

 flora necessary for its prosecution that so many additions have been made to the 

 forms previously known as British. Many local works have been issued in recent 

 years, often on a very high standard of excellence. Besides these larger works 

 scientific periodicals and transactions of field clubs and other societies teem with 

 records, some of them very brief, while others are of such size and compass that 

 they might have been issued as separate books. A few of both the books and 

 papers are little more than mere lists of names of species and varieties observed 

 in a locality during a brief visit; but usually there is an attempt at least to dis- 

 tinguish the native or well-established aliens from the mere casuals, if these are 

 mentioned at all. In respect of aliens or plants that owe their presence in a 

 district to man's aid, intentional or involuntary, their treatment is on no settled 

 basis. Every flora admits without question species that are certainly of alien 

 origin, even such weeds of cultivated ground as disappear when cultivation is 

 given up, as may be verified in too many localities in some parts of our country. 

 Yet other species are not admitted, though they may be met with here and there 

 well established, and at least as likely to perpetuate their species in the new 

 home as are some native species. 



Comparatively few writers seek to analyse the floras of the districts treated of 

 with a view to determine whence each species came and how, its relation to man, 

 whether assisted by him in its arrival directly or indirectly, whether favoured or 

 harmfully affected by him, its relations to its environment — especially to other 

 species of plants and to animals, and other questions that suggest themselves 

 when such inquiries are entered on. It is very desirable that a careful and exhaus- 

 tive revision of the British flora should be made on these and similar lines. In 

 such a revision it is not less desirable that each species should be represented by 

 a good series of specimens, and that these should be compared with similar series 

 from other localities within our islands, and from those countries from which it is 

 believed that the species originally was sprung. Such careful comparison would 

 probably supply important evidence of forms being evolved in the new environ- 

 ments, differing to a recognisable degree from the ancestral types, and tending 

 to become more marked in the more distant and longer isolated localities. An 



