-JVo. 1.1 GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 51 



Aracj<:^e. — Absent from the whole interior region; represented by 

 seven genera in the Atlantic flora, of which Peltandra and Orontium 

 are peculiar, and Sym^plocarpus, except that it is reproduced in Japan ; 

 on the Pacific coast only a relative of the latter, Li/sicMton, of which the 

 same species occurs in Japan. 



Lemnace^, Typhacb^. — Both nearly the same on the two sides of 

 the continent. 



Naiadace^. — In similar case, except that the Pacific coast adds 

 Lilcea and Phyllospadix. 



Alismace^. — ISTot dissimilar, except that the Atlantic flora has sev- 

 eral species of Sagittaria and the Pacific only one, but it has the Euro- 

 pean type of Damasonium. 



Hydkocharidaceje. — The Atlantic flora possesses Idmnohium and 

 ValUsneria as well as Anacharis ; the Pacific, only Anacharis; the 

 intermediate region none. 



BuRMANNiACE^. — Two Atlantic genera and species of South Amer- 

 ican afiQnity ; none in the western floras. 



Orchid ACE^. — Are much fewer in the Pacific flora than in the 

 Atlantic, and are wanting in the intermediate region, except on the 

 mountains, and there in mostly amphigaean species. The Atlantic flora 

 has the j)eculiar genera Tipularia and Arethusa (but the latter is in 

 Japan), and some peculiar Sahenarim ; the Pacific i)ossesses two Euro- 

 pean genera, Gephalanthera and Epipactis, but the latter is also in 

 Texas, and an European species of it has recently been detected in the 

 State of New York. 



Cannace^. — Two genera and three species in the southern part of 

 the Atlantic flora only. 



Amaryllidaceje. — Are represented in the Atlantic flora by five 

 genera, none of them peculiar, and several species. There are none in 

 the two western floras except Agave, and those of Mexican type, and 

 only along the southern border. 



Hjemodorace^. — Three genera, all strictly peculiar to the Atlantic 

 States. 



Bromeliaceje. — Tillandsia only along the Atlantic coast ; one spe- 

 cies north to Virginia ; others in Florida and its northern border. 



Iridace^. — Two peculiar genera in the Atlantic flora or its borders, 

 besides Iris and SlsyrincMum, which are more numerous in the Pacific 

 flora ; the former along the mountains between. 



Dioscoreace^. — A single Bioscorea, in the Atlantic flora only. 



Smilace JE. — A dozen species of Smilax in the Atlantic flora ; one of 

 them barely reaches the Eocky Mountains; a single and peculiar species 

 in Oaliforuia. 



KoxBXTRGHiACE..^. — Oroomm, a single species, in the Southern xVtlantic 

 States ; a close congener in Japan ; all other relatives Asiatic. 



LiLiACE^. — Here taken in the extended sense, are largely represented 

 <by twenty-four genera) in the Atlantic flora ; are not very few in the 



