NATURE 



{May 6, 1875 



possessions whose vegetable wealth botanists have under- 

 taken to describe in a systematic order, is due to various 

 causes, not the least of which is the enormous labour of 

 collecting and sifting the scattered literature bearing on 

 this subject. The books and short papers on the botany 

 of various parts of India are exceedingly numerous, and 

 several works have been commenced never to be com- 

 pleted. Dr. Hooker himself, in conjunction with Dr. T, 

 Thomson, published some years ago the first volume of a 

 Flora of India based upon a more elaborate plan than 

 that of the work now in progress, which departs from 

 that of the other Colonial Floras, Hooker's " Student's 

 Flora of the British Islands " having served as a model. 



In addition to British India proper, this work embraces 

 the territories of the Malayan Peninsula, Kashmir, and 

 Western Thibet ; but Afghanistan and Baluchistan, having 

 been taken up by Boissier in his " Flora Orientalis," are 

 not included. The total area under investigation'exceeds a 

 million square miles, exhibiting every variety of climate, 

 soil, and other conditions, and ranging from the sea- level 

 to an altitude of 19,000 feet, which is about the upper 

 limit of flowering plants. Dr. Hooker computes the total 

 number of species growing within this area at 12 to 14,000 

 which is doubtless not very] wide of the mark, judging 

 from the number reached up to the end of the Sapin- 

 dacece. 



In the first place we will give a glance at the contents 0£ 

 the present volume, which forms about a sixth part of 

 the whole work. Exclusive of an index of forty pages, it 

 extends to about ^oo pages, and includes descriptions of 

 2,250 species under 442 genera, belonging to forty-four 

 natural orders. These figures do not take in introduced 

 plants incidentally mentioned or fully described. Con- 

 trasting these numbers with those afforded by the flora of 

 tropical Africa up to the end of the Sapindacece, we 

 obtain some idea of the relative richness of the vegeta- 

 tion of tropical Asia, especially if we bear in mind that the 

 area of tropical Africa is more than six times the extent 

 of India. True, African vegetation is not so well known, 

 but future discoveries in the respective countries will pro- 

 bably not materially alter the proportions. The numbers 

 for tropical Africa, which we have added up in Oliver's 

 " Flora of Tropical Africa," are 945 species in 250 genera^ 

 and forty-five natural orders. It will be seen that the num- 

 ber of natural orders is almost the same, one more being 

 represented in Africa than in India. A very large propor- 

 tion of the species enumerated in the volume before us 

 are exclusively Asiatic ; we have not made an exact calcu- 

 lation, but should estimate it at ninety per cent. Of the 

 442 genera, 164 are, so far as our present knowledge goes, 

 pecuhar to Asia. The greater part of the peculiar genera 

 are tropical, and many of these, doubtless, still remain to 

 be discovered in New Guinea and tropical Austraha. The 

 mountains of Northern India have furnished our parks 

 and gardens with many useful and ornamental trees, &c. ; 

 e.g., Cedrus Deodara zxidi Pinus excelsa; and many others 

 might be introduced with a view to profit or pleasure. In 

 most cases, where possible, Dr. Hooker gives the altitudes 

 at which the species are known to occur ; but of course 

 this part must still be imperfect. We have made a list of 

 those species reported as growing «(5^t/^ 10,000 feet, and it 

 includes nearly 250 species, or about a tenth part of the 

 whole number. These belong chiefly to the Ranunculacea, 



Cruci/ens, and CaryophyllecE, and contain a large number 

 of endemic species ; the remainder being chiefly common 

 either to Siberia or the Alps of Southern and plains of 

 Northern Europe,^ including many common British plants. 

 We will not trouble the reader with many more figures, 

 but we may select a few more to give a general idea of 

 the vegetation up to the point reached in this volume. 

 Taking two or three examples of those orders consisting 

 mainly of herbaceous plants or climbing shrubs, we 

 \i?i.ve RantificnlacecE^ii^ species, or 5*2 per cent ; CrticifercE, 

 137 species, or about 6 per cent. ; Cnryophyllece^ 104 spe- 

 cies, or 4*6 per cent. ; and GeraniacecB, 165 species, or 7*3 

 per cent. Turning to the woody orders which characterise 

 the[tropical and sub-tropical regions, we have y4«^««f^(^, 190 

 species, or about 8*5 per cent. ; Dipterocarpecc (an almost 

 exclusively Asiatic family), 92 species, or about 4 per 

 cent.; GuttifertT 6\, TiliacecE io(), MeliacecB 83, OlacinecE 

 66, Celastrinece 105, and SapindacecE 70 species. Among 

 genera numerous in species we may mention Capparis 

 Garcinia, Grewia, Impatiens, and Vitis. Considerably 

 more than a hundred species of hnpatiens are described, 

 and about 75 of Vitis ; seven of the former genus ascend 

 above 10,000 feet, and nearly all of them are very restricted 

 in their geographical area. In tropical Africa there is 

 about the same number of species of Vitis, but only one 

 or two are common to both regions, the others being 

 endemic. 



So far we have confined ourselves to an attempt to 

 indicate the interest of the work as a contribution to 

 phytogeography ; its usefulness in applied botany cannot 

 be over-estimated. It would not be difficult, it is true, to 

 point out a great many little defects and inequalities in 

 elaborating the materials at their disposal by the different 

 contributors. But those whose experience is least in this 

 branch of botany are aware of the difficulties encountered 

 at every step. In the first place, the limitation of species 

 must be more or less arbitrary, and it is by no means an 

 easy task to settle the limits, in this case especially, on 

 account of the large number of forms described as species 

 by botanists! of all nations in innumerable books and 

 journals. The view here taken of species is a broad one ; 

 hence we find that'there is an average of two synonyms 

 to each species, and in some instances the array of names 

 is something quite formidable. Of course many of these 

 synonyms result from individual views respecting generic 

 limits. As to genera, there is little deviation from Hooker 

 and Bentham's " Genera Plantarum," though an examina- 

 tion of a large number of specimens has frequently neces- 

 sitated a modification of the diagnoses of certain genera. 

 As to " polymorphous species," the forms readily distin- 

 guished are briefly characterised as varieties ; but it is 

 assumed that the extreme forms collected under one 

 species are united by every intermediate gradation, so 

 that it is not possible in practice to say to which variety 

 some forms should be referred. We have already men- 

 tioned that Hooker's " Students' Flora " has been followed 

 mainly in the style of arranging the matter, and this no 

 doubt is an improvement in some respects on the Colonial 

 Floras ; but the absence of keys to the species of each 

 genus, in our opinion, is not compensated for by the 

 change. In the "Students' Flora" the synonyms are 

 given in italics, and readily catch the eye ; but in the 

 " Flora of India " they are printed in the same type as the 



