NORTH AMERICAN FLORA. 269 



certain admixture of northern elements.) To the first type I 

 refer such trees and shrubs as Asimina, sole representative of 

 the Anonacece out of the tropics, and reaching even to lat. 42° ; 

 Chrysobalanus, representing a tropical suborder; Pinckneya, 

 representing as far north as Georgia the Cinchoneous tribe; 

 the Baccharis of our coast, reaching even to New England ; 

 Cyrilla and Cliftonia, the former actually West Indian ; 

 Bumelia, representing the tropical order SapotaceoB ; Big- 

 nonia and Tecoma of the Bignoniacea ; Forestiera in Ole- 

 acece ; Persea of the Laurineoe ; and finally the Cactacece. 

 Among the herbaceous plants of this set I will allude only to 

 some of peculiar orders. Among them I reckon Sarracenia, 

 of which the only extra-North American representative is 

 tropical- American, the Melastomacccv, represented by Rhexia ; 

 Passiflora (our species being herbaceous), a few representa- 

 tives of Loasacece and Turner acece, also of Hydrophyllacea ; 

 our two genera of Burmanniacece ; three genera of Ha mo- 

 dor acece ; Tillandsia in Bromeliacece ; two genera of Ponte- 

 deriacece ; two of Commelynacece ; the outlying Mayaca and 

 Xyris, and three genera of Eriocaulonaccce. I do not forgel 

 that one of our species of Eriocaulon occurs on the west coast 

 of Ireland and in Skye, wonderfully out of place, though <>n 

 this side of the Atlantic it reaches Newfoundland. It may be 

 a survival in the Old World ; but it is more probably of 

 chance introduction. 



The other set of extra-European types, characteristic of the 

 Atlantic North American flora, is very notable. According to 

 a view which I have much and for a long while insisted on. it 

 may be said to represent a certain portion of the once rather 

 uniform flora of the arctic and less boreal zone, from the late 

 Tertiary down to the incoming of the Glacial period, ami 

 which, brought down to our lower latitudes by the gradual 

 refrigeration, has been preserved here in eastern North 

 America and in the corresponding parts of Asia, but was lost 

 to Europe. I need not recapitulate the evidence upon which 

 this now generally accepted doctrine was founded ; and to 

 enumerate the plants which testify in its favor would amount 

 to an enumeration of the greater part of the genera or sub- 



