XXI THE AGE OF COMPOSITE 243 



the islands and not from the islands as well {Intr. Bot. Chall. Exped... 

 p. 66) ? I need scarcely add that the same question presents itself 

 with all the other peculiar genera of these islands, and in fact with 

 endemic genera all over the world. What can be stranger, it may 

 be remarked, than the limited distribution of the Pandanaceous 

 genus Sararanga in the Western Pacific, although suited for 

 dispersal by frugivorous birds. This is not, indeed, a special 

 difficulty connected with oceanic islands ; it applies to the whole 

 plant-world ; yet it is possible that, as it is exhibited by the Compo- 

 sitas in these islands, we may be in a better position to grapple 

 with the problem. But before doing so it will be requisite to look 

 a little closer at these early Hawaiian genera of the Compositae. 



The distribution within the archipelago of the genera and 

 species of the early Compositae of Hawaii is worthy of notice 

 from the light it throws, not only on the relative antiquity of the 

 genera, but also on the subsequent conditions of isolation. Of the 

 nine genera here referred to five are distributed over most of the 

 islands of the group. These include all the genera possessing a 

 number of species, namely, Tetramolopium with seven species, 

 Lipochaeta with eleven, Campylotheca with twelve, Dubautia with 

 six, and Raillardia with twelve species. Of the four genera 

 remaining all have only two species, and are restricted to two or 

 three islands, Remya and Wilkesia being in both cases found in 

 Kauai and Maui, whilst Argyroxiphium is confined to the adjacent 

 islands of Maui and Hawaii, and Hesperomannia to those of Oahu, 

 Lanai, and Maui. These four genera that are restricted to only 

 two or three islands are the same before referred to as regarded 

 by Hillebrand as the oldest, partly on account of their isolated 

 generic position, and partly because in each case they only possess 

 two species. 



Although the early Hawaiian Compositse were evidently 

 originally transported to most of the islands of the group, it is 

 noteworthy that their subsequent isolation from the rest of the 

 world has in the later ages been repeated within the limits of the 

 archipelago. Of the 56 species, all of which are now endemic, 

 28, or just half, as shown in the table on the following page, are 

 confined to a single island. Of the remainder, almost all are 

 restricted to two or three adjacent islands. Hillebrand gives 

 only a solitary species, Lipochseta connata, as occurring in all 

 the islands. This suspension, to a great extent, of the means of 

 dispersal between the islands is also strikingly illustrated by the 

 Lobeliacea;. 



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