300 



EDMUND W. SINNOTT AND IRVING W. BAILEY 



This conception of the dicotyledonous herb as a comparatively 

 recent type of plant which has been developed extensively in the 

 north temperate zone during the Tertiary and has spread thence 

 far and wide over the globe also leads us to some interesting geo- 

 graphical conclusions. Those regions, such as southern Asia and 

 Mexico, which have been invaded, at least in their more temperate 

 portions, by a flood of northern herbs, have in all probability had a 

 nearly or quite continuous land connection with northern Eurasia 

 or North America during Tertiary time. Other regions, such as 

 Australia, New Zealand, South America, and South Africa, where 

 there is a markedly smaller percentage of herbs in the vegetation, 

 have apparently had a much less intimate connection with the great 

 land mass of the north temperate zone during the Tertiary. This 

 is particularly true of certain oceanic islands, notably Hawaii, the 

 Polynesian group, Juan Fernandez, the Canaries, St. Helena, 

 Socotra, Mauritius, and the Seychelles, on which the percentage 

 of herbs is much smaller than on the adjacent mainland. In these 

 insular floras practically all the herbs belong to species which 

 also occur on the near-by continent; and almost the entire body of 

 the endemic genera, presumably the most ancient portion of the 

 flora, is composed of woody plants, as is shown in Table III. 



TABLE III 



Total 



Herbs 



Percentage 

 Herbs 



Hawaii — 



Species of non-endemic genera 

 Species of endemic genera. . . . 



Fiji — 



Species of non-endemic genera 

 Species of endemic genera .... 



Juan Fernandez — 



Species of non-endemic genera 

 Species of endemic genera .... 



St. Helena — 



Species of non-endemic genera 

 Species of endemic genera .... 



Mauritius and the Seychelles — 



Species of non-endemic genera 

 Species of endemic genera .... 



339 

 243 



543 



57 

 17 



34 



7 



524 

 63 



117 



15 



191 

 3 



34 

 8.6 



15 

 o 



47 

 o 



44 



36 

 4-7 



This paucity of herbs, particularly of annuals, on oceanic islands 

 was noted long ago by Darwin, Hooker, and others, and was ex- 



