No. 1.] GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 41 



SENECiONiDEiE.— Somewhat equally distributed overtlic world; oft'er 

 little for remark. There is no peculiar type in the Atlantic flora nor 

 east of the Kocky Mountains, hut beyond them Tetradymia and Psathy- 

 rotes are truly characteristic of the Great Basin ; RaillardcUa (the rel- 

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

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

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



CYNAROiDEyis.— Are restricted to Cniciis, of which the Atlantic States, 

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

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

 of species (more or less pecnliar), and the showy Centaurea Americana^ 

 now well known in cultivation, which inhabits the plains of Arkansas 

 and Texas. 



MuTisiACB^ (including all the Bilahiatiflonv of De Candolle). — Aflect 

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

 America and Asia. In the former most are of the Texano-Arizouian 

 •district — Leria, Trixis, Perezia — and are outliers of the Mexican flora ; 

 but one of the latter genus fairly reaches California, and the original 

 Chaptalia is of the Atlantic Southern States. 



CiCHORACE^, or the LiguUfiorcv. — A very moderate number of the 

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

 Cynilua are peculiar to the Atlantic flora or its borders, Pyrrhojxippiis 

 to this and the nearer parts of Mexico, and N'abalus has only one extra- 

 neous northwestern species; but the open western country nourishes 

 the greater x>art of our representatives of this tribe. From the plains 

 to the Pacific spreads the genus Troximon, accompanied by Lygodesmia 

 and StepJianomeria, and even by Malacotlirix ; Glyptopleura, Anisocoma, 

 and mainly Calycoseris are peculiar types in the Great Basin ; and fifteen 

 species of Malacotlirix are peculiar, or nearly so, to the Pacific flora, 

 which has also Bajinesqiiia, Apargidium, and PJialacroseris. The paucity 

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

 wonder and a relief to botanists. 



LoBELiACEJE. — Lohelia is essentially wanting from the Pacific and 

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

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

 Doicningia, JloiceUia (an aquatic plant of Oregon), PaJmerella, and the 

 curious N'cmacladus. It has also a peculiar Laiirentia, which extends 

 eastward to the Eocky Mountains, where it is the only representative of 

 the iamily. 



Campanulace^. — Are not numerous; but Campanula has a few 

 rei)resentatives in all three floras (in the interior only on the mountains) ; 

 Specularia has fewer; and two genera of single species, Githopsis and 

 Heterocodon, are i)eculiar to the Pacific flora. 



Ericaceae. — This important order needs to be considered under its 

 suborders. 



Vaccines. — In the northern hemisphere aflect the eastern side of 



