Vo. 1 GRAY AND HOOKER OH Mi! BOCKT MOUNTAIN FLORA. 11 



si:ni;iii).\ii)i:.i:.- Somewhat equally distributed over the world; offer 

 little for remark. There is n<» peculiar type in the Atlantic flora nor 

 east of tlie Rocky Mountains. i»ut beyond them Tetradymia and Psathy- 

 s an- truly characteristic of the Great Basin; RaillardeUa (the rel- 

 atives of which are only in the Sandwich or Hawaiian [slands) is pecu- 

 liar to the high sierra Nevada, and Luina to the Pacific coast ranges. 



Western North America is. morever. the headquarters of Arnica. 



c\ \aki»ii>i:.i:. — Are restricted t«> ('nuns, of which the Atlantic States, 

 the Rocky Mountains and their accessory western ranges, and the Pa- 

 citic side of the continent have about an equal and a moderate number 

 et' species (more or less peculiar), and the showy Centaurea Americana, 

 now well known in cultivation, which inhabit- the plains of Arkansas 

 and Texas. 



MrnsiACE.K (including all the Bilabiatiflorai of De CandoHe). — Affect 

 the southern hemisphere, hut come into a temperate region both in North 

 America and Asia. In the former most are of the Texano-Ari/.onian 

 district — Leria, ZHrta, Perezia — and are outliers of the Mexican flora : 

 l>ut one of the latter genus fairly reaches California, and the original 

 otalia is of the Atlantic Southern States. 



ClCHORACEJB, or the lAguliflorce. — Avery moderate Dumber of the 

 sixty genera are indigenous to North America. Apogon, Krigia, and 

 Cynthia are peculiar to the Atlantic flora or its borders, Pyrrhopappus 

 to this and the nearer parts of Mexico, ami Nabalus has only one extra- 

 neous northwestern species; but the open western country nourishes 

 the greater part of our representatives of this tribe. From the plains 

 tit the Pacific spreads the genus Troximon, accompanied by Lygodesmia 

 ami Stephanomeria, and even by Malacothrix; Glyptopleum. Anisocoma, 

 and mainly Gahjcoseris are peculiar types in the (heat Basin ; and fifteen 

 species of Malacothrix are peculiar, or Dearly so, to the Pacific flora, 

 which has also Bafinesquia, Apargidium, and Phalacroseris. The paucity 

 of the large and difficult Old World genus Hieracium in America is a 

 wonder and a relief to botanists. 



LOBELIACR& — Lobelia is essentially wanting- from the Pacific and 



the Rocky .Mountain floras, but well represented in that of the Atlantic. 



Instead, the Pacific flora is characterized by four peculiar genera, 



\ingia ) Howellia (an aquatic plant of Oregon), Palmerella^ and the 



curious A'' macladus. It has also a peculiar Laureutia, whieh extends 



aid t<» the Rocky Mountains, where it is the only representarr 

 the family. 



< \MrA\n.A< i;.i;. — Are not Dumerous; but Campanula has a few 

 representatives in all three floras (in the interior only on the mounts 



ilarta has fewer; ami two genera of single species, OithopeU ami 

 //. u rocodon, are peculiar t«» the Pacific flora. 



Erica* i:.i.. — This important order Deeds t<> be considered under it> 

 ordei s. 



Vacclnejk. — In the northern hemisphere affect the eastern sideoi 



