Vo 1] GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 45' 



been found in the Great Basin), and excepting the Tiquilia section of 

 Coldenia, which extends to the northwestern verge of the interior wood- 

 less region. The genera and species are few in the Atlantic flora. Its 

 only characteristic genus is Onosmodium; the yellow-flowered and showy 

 Litliosperma of the section Batschia it shares with the plains. The great 

 genus of the whole Kocky Mountain flora, though shared with the Pa- 

 cific, is EntricMum ; t]ie characteristic genus of the Pacific flora, of which 

 its neighbor ta]ies a part, is Amsinclcia. Merten^ia has most of its spe- 

 cies in the Eocky Mountains and their accessories, yet the finest of them' 

 is M. Virginica, ijeculiar to the Atlantic States. Pectocarya may have 

 been brought from Chili to California. Some peculiar genera of the 

 Arizouia|i flora are hardly within our scope. 



CONVOLVULACE-as. — There are no peculiar genera in North America, 

 and nothing nota|^l(B in distrihi^tjlpii. Tlieje arp many more Atlantic- 

 thap Pacific specie^. 



SoLAJSTACE^. — As to truly indigenous species, arp few north and east of 

 T^xas, and not nupierous through the western portions of the country. 

 Physalis is the largest genus. The only peculiar genera are Chamce^Q- 

 racha and the very little known Oryctes, neither of salient character^, 

 both of the interior region. Into the southern part of the Kocky Mount- 

 a^RS extend from Mexico two species or forjns of the Potato type. 



ScROPHULAEiACE^. — North America has 37 indigenous genera of 

 this very large order, several of them numerous in species. They are 

 fewest in tlie Atlantic flora, which yet has some peculiar genera, and it 

 is noteworthy that only one of them {Schwalbea) is of near affinity to- 

 Japano-Himalayan types. Throughout, the types which are not distinct- 

 ively American are rather European, Mimulus, however, being an ex- 

 ception. Thus, in California there is a remarkable development of the 

 genus Antirrhinum. Of the several tribes, there is one which is particu- 

 larly characteristic of the Atlantic flora, namely, that which contains 

 Gerardia (of over 20 species), and is augmented by 2[acrantJicra, Sey- 

 meria, and Buclinera. Some species abound on the eastern part of the 

 plains, but none reach the Eocky Mountains or appear in the (;onntry 

 beyond them. Of genera which are sparingly represented in the At- 

 lantic flora or near its borders, and are in fuller strength westward, the 

 more characteristic are Collinsia, and the great genus rentstemon, witii 

 about 4 species at the east and nearly 40 in the Pacific flora ; Mimiiltts, 

 with;? Atlantic and at least 23 Pacific species; Synthyris; CastcUcia, 

 with 3 or 4 Atlantic and about 20 western species ; Orthocarjms with one 

 species on the northeastern plains and 24 in the western floras, chiefly 

 on the Pacific side, while its relatives hi Cordylanthus add half as many 

 more. So Pcdicularis, with only 2 Atlantic species, increases westward 

 to over 20. 



OROBANCiiACEiE.— The four North American genera are wholly dis- 

 tinct from the European, and from the Asian also, except for an Eastern 

 Asian species of Boschnialcia. Here also, although two of the genera. 



