No.-i.l GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 31 



PoLYaALACE^. — Eepreseuted by Polygala. The Atlantic flora is rich, 

 iu species, all of them peculiar; the Pacific flora has only two. of a 

 l)eculiar type. The Texano-Arizonian region has several, some of them 

 Mexican, but from both the mountains and valleys of our belt the genus 

 and the order are nearly absent. 



Keameriace^. — Should be separately reckoned, whatever view be 

 taken of the affinity of the warm-American (chiefly Mexican) genus 

 Krameria. One species reaches the plains of Arkansas, and has obtained 

 a lodgment on the coast of Florida ; two or three more extend along the 

 Mexican frontier, but hardly infringe upon the region under consid- 

 eration. 



Frankeniace^. — Of a single genus, of warm temperate and subtrop- 

 ical coasts; has aCalifornian and Arizonian species; no Atlantic repre- 

 sentative, but there is a quite peculiar species at the southeastern base 

 of the Eocky Mountains. 



Caryophyllace^. — The Silenew are feebly represented (by Silene 

 only) in the Atlantic flora, yet by peculiar species ; are nearly wanting 

 from the Great Plains, scanty iu the Eocky Mountains, but of increas- 

 ing number and diversity as the Pacific flora is api^roached. The Al- 

 sinece, moderately numerous, call for no remark, except for the increased 

 number of species of Arenaria in the interior flora, most of thenj peculiar. 

 Stipulicida is of a single strictly Atlantic species. 



Tllecebrace^. — ISTo where very numerous, but most of the species and 

 genera in the Old World. ParonycJiia is represented in the Atlantic 

 flora ; also in that of the plains and the eastern part of the liocky 

 Mountains. Anychia and Siphonychia are peculiar to the Atlantic flora ; 

 Pentaccvna to that of the Pacific coast, extending to Chili. Acliyronychia^ 

 a remarkable genus, of one species, belongs to the Arizonian rather 

 than the California flora. 



Portulacaca^. — This may be regarded as an American order, al- 

 though the Purslane has accompanied man all over the world. The 

 single species of Montia has an immensely wide distribution over the 

 cool parts of the world. One of Glaytonia and several of Galanclrinia are 

 Australian, and two small genera are South African. So, as relates to 

 distribution, it is a very suggestive order. The Atlantic States have 

 only the two earliest kno^ai species of Glaytonia and a Talinum ; !N"ew 

 Mexico has a peculiar genus {TaUnopsis), too like an African one; the 

 Eocky Mountain region has the characteristic and remarkable genus 

 Lewisia, and more species of Glaytonia, &c. ; Spraguea and Galyptridium 

 are peculiar to the whole country west of the Eocky Mountains proper ; 

 Calandrinice are all western ; and the Pacific flora contains most of the 

 species of Glaytonia. 



Elatinaceje. — Two of our three species of Elatine occur in the At- 

 lantic, Eocky Mountain, and Pacific floras; one is restricted to the 

 latter. The Texan Bergia very sparingly occurs in the Great Basin and 

 on the Pacific coast. 



