32 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Yol.Yl. 



Hypericace^. — Eepresented by three genera, of wliicli the two 

 small ones, Ascyrum and Ulodes, are peculiar to the Atlantic flora 

 (except European relatives of the latter), which is rich in endemic 

 species of Hypericum ; the Pacific flora has three or four endemic species 

 of the latter, the intervening region nothing of the order. 



Ternstrcemiace^. — This Eastern American and Eastern Asian order 

 is represented only east of the Alleghanies, and by Stuartia, two species 

 (the third in Japan),- Gordonia, two species, and several hardly genuine 

 species in tropical Asia. 



Malvace^. — This is one of the great and cosmopolitan orders, of 

 which North America possesses a fair but not excessive representation. 

 The species and forms here increase in number south westward. Indige- 

 nous lilants only being regarded, no genus is common to North America 

 and Europe excepting Zavatera, represented by two or three singular 

 and mostly shrubby species of the Californiau coast. Napcea is strictly 

 peculiar to the Atlantic flora, as also is the unique 8ida Napcea. Callir- 

 rhoe is i)eculiar to the borders of the same district and the plains adja- 

 cent. Sidalcea is peculiar to the Eocky Mountain and Californian floras. 

 IngenJiouzia (which is Thurheria) belongs the Western Arizonian flora. 

 Malvastrum and Spliceralcea (too near generically) are numerous in spe- 

 cies on the j)lains and through the valleys of the Rocky Mountain region. 

 Kosteletzkya is represented on the Atlantic coast, but most of the species 

 are Mexican. 



BojVEBACB^. — Fremontia Californica belongs wholly to the forest dis- 

 trict of the Sierra Nevada, and its only relative is Gheirostemon, the 

 Hand-flower of Mexico. 



TiLiACE^. — Excepting one or two outlying jilants on the southern 

 borders, this order is represented only by the genus Tilia, in two species 

 of the Atlantic States, which hardly cross the Mississippi. 



LiNACEJE. — Three or four Atlantic species of Linum, as manj^more on 

 the plains or Eocky Mountains, one species from the plains to the Pa- 

 cific coast, and the same is an Old World species, or nearly so ; and, 

 moreover, in California and Oregon an unique group of seven species 

 (Hesperolinon), in which the carpels are reduced from five to three, or 

 even two. 



Zygophtllace^. — Leaving out the species of Trihulus or KaUstroe- 

 mia and the Texano-ArizOnian representatives, among which Fagonia 

 Galifornica should be ranked, notwithstanding the specific name, only 

 the Creosote Bush remains, Larrea Mcxicana, a shrub of the Mexican 

 plateau, which has passed into or near the southern border of our belt 

 all along from Texas to California. 



GrERANiACE^. — In the restricted sense, are few in North America, 

 consisting only of a few species of Geranium; the eastern and western 

 perennial ones diflerent 5 a biennial species of a weedy character is scat- 

 tered over the continent. 



LiMNANTHE^. — Are exclusively North American ; Limnanthes, of two 



