xii INTRODUCTION. 
Genera. Species. Distribution. 
Acacia . . . . . 482 Generally in warm regions; numerous in Australia. 
Eupatorium. . . . 400 Temperate and subtropical regions except Africa and Australia, but 
most numerous in South America. 
Erica. . . . . . 400 Europe, Mediterranean region, and very numerous in South Africa. 
Peperomia . . . . 400 All over the tropics with few extensions into temperate regions. 
Epidendrum . . . 400 Tropical and subtropical America; the Galapagos Islands. 
Cyperus. . . . . 400 All warm regions; rarer in temperate. 
Vernonia. . . . . 380 ‘Tropics generally; rare in temperate regions. 
Cassia. . . . . . 338 All tropical countries; rare in temperate regions. 
Loranthus . . . . 330 Warm regions; rarer in temperate. 
Centaurea . . . . 820 Europe, Africa, and Asia; six in America; one in Australia. 
Myrcia . . . . . 800 Tropical and subtropical America. 
Miconia. . . . . 800 ‘Tropical and Andine America. 
Mamillaria . . . . 800 Mexico to Bolivia. 
Mesembryanthemum. 3800 Mediterranean region to Cape and Australasia; chiefly Cape. 
Ipomea. . . . . 800 All warm and most temperate countries. 
Quercus. . . . . 800 North temperate and subtropical regions and extending to New 
— Guinea. 
Totals. . 28 . 12400 
These twenty-eight genera contribute 13 per cent. of Bentham and Hooker's estimate 
of the total number of species of flowering plants. With regard to the actual numbers 
given, some of them, at least, are considerably below what the authors would them- 
selves probably distinguish as species. Thus, for instance, Bunge, in a monograph of 
the Old-World species of Astragalus, published since the corresponding part of the 
‘Genera Plantarum,’ describes 971 species, and he has subsequently increased the 
number to upwards of 1000; and there are at least 200 American species. The 
estimated number of species of Piper and Peperomia is perhaps in excess of that 
actually existing. . 
There is one more feature in the world distribution of flowering plants demanding 
attention, and that is the wide or peculiar range of certain species, which possess no 
special means of dispersion by animals or birds or the elements, and which are most 
unlikely to have been aided, intentionally or unintentionally, by man. Such species 
are not few in number, but a sample of them will be sufficient as an illustration of 
distribution, and a selection may be made from those inhabiting Britain. Sir Joseph 
Hooker has discussed this phenomenon with greater fulness than we have space to do 
in this place *. 
.Radiola millegrana . . . 1. 1. 1 we Europe, North Africa, and mountains of Tropical 
Africa. 
Alchemilla vulgaris. . . 2. 2... us Western Europe to N.E. India, Labrador, Green- 
land, and Alps of Victoria, Australia. 
* ¢ Flora Tasmanie,’ i. Introductory Essay, p. xciv; and also “ On the Plants of the Cameroons Mountains,” in 
the Journal of the Linnean Society, Bot. vii. p. 178. 
