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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 such marked influence on all vegetation. It has not, however, been explained to the satisfaction of those who are familiar with the effect why the monsoons produce it.
It is again unnecessary to dwell 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 opportunity to discuss them.
Plan of the flora.—For the reasons given in the preface, the descriptive 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 all 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 knowledge of the flora.
- The examination of herbaria containing Chinese plants and the extraction and publication of new Kwangtung records.
- The exploration of the districts indicated on the map as unknown and the record of their flora and botanical features.
- The further investigation of the more accessible parts.
- The location of doubtful sites of old collections.
- The supply of habitats, colours of flowers and time of flowering, where missing,
- The compilation of a Flora dealing with the Mosses, Algae, Fungi and other classes of vegetation not dealt with in this volume.
