10 



circumstances, may have given rise to a system of areas, to some 

 extent botanically isolated, and each with an element of peculiar 

 forms adapted^to its phenomena. Thus north-east and south-west 

 aspects, even^on the same mountain, support markedly different 

 floras, that of the latter being far less luxuriant. It can hardly be 

 doubted that this differentiation is connected with the monsoons 

 which blow from the two quarters indicated for nearly half the year 

 each, with suchjmarked influence on all vegetation. It has not, how- 

 ever, been explained to the satisfaction of those who are familiar 

 with the effect why the monsoons produce it. 



It is again unnecessary to dweU on the rigorous selection that 

 must have occurred during past ages among the coastal ranges of 

 those forms which were adapted to survive typhoons. But it is 

 only intended here to indicate some of the ecological problems 

 which await students in this province, at present facts are not 

 available for their full consideration nor would this be the oppor- 

 tunity to discuss them. 



Plan of the flora. — For the reasons given in the preface, the des- 

 criptive part of the Flora has been reduced to the smallest limits 

 compatible with the object of enabling the collector to determine 

 his plants. The following were deemed sufficient for this purpose. 

 1. A key to the Natural Orders. 2. A key to the genera of each 

 Natural Order. 3. A key to the species of each genus, taken in 

 the order of the Genera Plantarum. 4. An enumeration of the 

 species. The latter comprises (a) the Latin name, following in 

 practically aU cases, the nomenclature of the Index Kewensis, (b) 

 the most accessible good description known, (c) the habitat and 

 localities, (d) the colour of the flower where necessary, (e) the month 

 of flowering. 



Summary of desiderata. — From the foregoing pages may now be 

 selected the principal work which remains to be undertaken to 

 advance our fcaowledge of the flora. 



1. The examination of herbaria containing Chinese plants and 

 the extraction and publication of new Kwangtung records, 



2. The exploration o'f the districts indicated on the map as 

 unknown and the record of their flora and botanical features. 



3. The further investigation of the more accessible parts, 



4. The location of doubtful sites of old collections. 



5. The supply of habitats, colours of flowers and time of flowering, 

 where missing, ^' 



6. The compilation of a Flora dealing with the Mosses, Algae, 

 Fungi and other classes of vegetation not dealt with in this 'volume! 



