XXI 



THE AGE OF COMPOSITE 237 



other writers, and such as are in accordance with the facts of distri- 

 bution given in the Index Kewensis. Most ancient of all are the 

 genera Remya, Argyroxiphium, Wilkesia, and Hesperomannia, 

 which, although belonging to tribes that only occur on the American 

 continent, as in the Mexican region, stand quite isolated, and, as 

 Dr. Hillebrand remarks, probably belong to the oldest denizens of 

 the Hawaiian Islands. It is noteworthy that these four ancient 

 genera only contain two species apiece, a circumstance that favours 

 their priority in point of age. 



The American affinities, however, are not always of the charac- 

 ter that we might have expected. Thus, it was remarked by Mr. 

 Bentham that although the tribe Mutisiaceae attains a great de- 

 velopment in South America, and especially in Chile, its only 

 representative in the Pacific islands is the very rare arboreous 

 Hesperomannia of Hawaii. 



Rather less isolated in character, and we would presume there- 

 fore of somewhat less antiquity, are the two closely allied genera 

 of Raillardia and Dubautia, which have a close relative in Raillar- 

 della of the Sierra Nevada in California. Then we come to the 

 three genera, Tetramolopium, Lipochaeta, and Campylotheca, that, 

 being still in touch with the world outside, may be regarded as 

 the latest arrivals of the early genera of the Compositae. Tetramo- 

 lopium, concerning which botanists were unable to agree, would 

 seem, according to the Index Keivensis, to possess Mexican and 

 Ecuadorian as well as Hawaiian species. Lipochaeta, nearly re- 

 lated to other American genera, contains a dozen species, of which 

 eleven are found only in Hawaii, whilst the twelfth occurs, according 

 to the Index Kewensis, in California, and, according to Dr. Hille- 

 brand, in the Galapagos group. Of the generic value of Campylo- 

 theca there seems a doubt, and its distinctness is scarcely recog- 

 nised in the Index Kewensis. It is, however, closely allied to 

 Coreopsis, an American genus represented, according to Drake del 

 Castillo, in the Marquesas. 



In the Tahitian region, that is to say in Eastern Polynesia, the 

 genus Fitchia alone belongs to the early age of the Compositae, so 

 characteristic of Hawaii. Indications of the former widespread 

 range of the genus over this region of the South Pacific are afforded 

 by its being now represented by two species in Tahiti and by one 

 species in Rarotonga, localities nearly 700 miles apart. It was 

 thus regarded by Bentham, who saw in it a solitary remnant of the 

 ancient South Pacific flora. Like the Hawaiian genera, as shown 

 below, it is often restricted to the higher levels. Botanists differ 



