JTo. 1.1 GEAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 39 



EuBiACE^.— This vast order of over 300 genera and 4,000 species 

 forms an insignificant feature in North America, and in the northern 

 temperate zone throughout. But the poverty of the Eocky Mountain 

 and the Pacific floras is eltreme. There are some species of Galium 

 in all, and Ceplialantlius is on both sides of the continent and of south- 

 ern extension. Besides, the Pacific flora has only the peculiar mono- 

 typic genus Kelloggia, with no near relative in the northern hemisphere. 

 The Atlantic flora nearly monopolizes the genuine species of Houstoniaj 

 and its specially characteristic genus is Mitchella, which is repeated in 

 a very similar species in Japan. 



YALEEiANACEyT5. — A Small family, is here unimportant. The only 

 peculiar genus is Plectritis of the Pacific coast and that of Chili. 



Composite.— No detailed analysis can be expected here of the dis- 

 tribution of an order which is thought to make up one-tenth of flowering 

 plants and which composes a still larger proportion of those of North 

 America. Yet a few points may be brought to view, taking the tribes 

 separately. 



VERNONiACEyE. — Are known only in the Atlantic region, the princi- 

 pal genus, Vernonia, however, extending over the prairie border of the 

 plains. Stol-esia is one of those strictly peculiar genera of a single spe- 

 cies with which the Atlantic flora abounds. 



EuPATORiACE^. — This is almost an American tribe, the maximum in 

 South America, the minimum in our Pacific Territory, which has only 

 four or five species. But into the Eocky Mountains and the Great 

 Basin extends, more largely than into the Pacific flora, the genus Brick- 

 ellia, founded on an outlying species of the Atlantic flora, yet mainly a 

 Texano-Mexican genus. But the Atlantic flora is better supplied, and 

 with iDeculiar genera, viz, Sderolepis, Trilisia, Carjihephorus (the South 

 California species is hardly congeneric), the fine and rather large genus 

 Liatris, which, however, reaches nearly to the Eocky Mountains and 

 into Mexico, and Ktihnia, which is in the same case. Garheria of Flor- 

 ida, taken from. Liatris, is too southern to be i)roperly counted. The 

 great genus Eupatorium is also well represented on the Atlantic side, 

 and here only is the northern extension, in a single species, of the huge 

 South American genus Mikatiia. 



AsTEROiDEiE. — Are eminently American, and in no other single dis- 

 trict are they so numerous as in the belt across the continent which is 

 under consideration. Aster, Solidago, and Bigelovia are the great genera ; 

 Aiilopapinis, Chrysopsis, Erigeron, and Tozcu.sentZi'a are next in importance. 

 About four- fifths of the Asters and SoVidagos belong to the Atlantic flora, 

 with some extension into the plains beyond, and there also are more 

 species and forms (but fewer individuals) of Chrysopsis; the amphigiien 

 genus Erigeron has its fullest development and diversification in our \\est- 

 ern regions; Aplopappus is divided between our Kocky Mountain fiora 

 (with southward extension and into that of the Pacific) and that of Chili. 

 Townsendia and Bigelovia are the most characteristic genera of tin- \\liole 



