BOTANICAL BEGIONS. 679 



Esculents $c. Melongena, Tomato, Anise, Coriander, Cotton, White 

 Mulberry, Saffron, Sumach, Lupins, Sainfoin. 



CJmracteristic forms. Sempervivum arboreum, S. canariense, S. tor^- 

 tuosum, &o., Ilex Perado, "Cacalia, Kleinia, Sonchus fruticosus, Arbutus 

 callicarpa, Ardisia excelsa, Ceropegia aphylla, Echium giganteurn, &c., 

 Laurus foetens, Euphorbia balsamifera, E. canariensis, Myrica Faya, 

 Pinus canariensis. 



4. Region of Asteres and Solidagines (Northern North-American, or 

 Michaux's Region). 



Mean temperature, 9-59 Fahr. (12-15 C.). 



The northern part of this region corresponds to the Europaso-Siberian 

 region of Grisebach (p. 077), the Califoruian coast represents the Medi- 

 terranean region, while the central prairies are the analogues of the Asiatic 

 steppes. The American forest region has a lower temperature than that 

 of Europe. New York has about the summer temperature of Rome and 

 the winter temperature of Copenhagen. The United States Flora, accord- 

 ing to Gray and Hooker, consists of three main elements, an endemic 

 American, a European, and an Asiatic ; while that of the temperate Old 

 "World is, in a continental point of view, binary Europe and Asia having 

 many types in common, but very few representatives of the strictly Ame- 

 rican flora. The distribution of North-American plants, unlike the Euro- 

 pean, is mainly in a meridional direction, the difference of the floras of the 

 Eastern, Central, and Western States being wonderfully great. The 

 European components extend over the whole breadth of the continent, 

 diminishing, however, to the westward. The American components pro 

 sent many localized genera, inhabiting the Eastern, Central, and Western 

 States respectively ; they increase in numbers and peculiarity, as also in 

 restriction of range, towards the west. The Asiatic components are 

 found both in the Eastern and Western States, but hardly at all in the 

 Central ; and some of them are common to both the east and west, while 

 others are peculiar to each. But whereas the European components 

 prevail on the side towards Europe, the maximum of Asiatic represen- 

 tation is on that remote from Asia. This has been conspicuously shown 

 by Gray's discovery, in the Eastern States, of single representatives of 

 Japanese genera previously supposed to be monotypic ; and what is most 

 noteworthy is, that such representatives are in some cases extremely rare 

 local plants, found in single and very restricted areas, indicating a dying- 

 out of the Asiatic representation in America. 



Character. More species of Coniferse and Amentaceae than in the second 

 region, but fewer Umbelliferae, Cruciferse, Cichoraceag, and Cynareas. 



Genera. Hydrastis, Sanguinaria, Hudsonia, Ptelea, Robinia, Gymno- 

 cladus, Purshia, Gillenia, Decodou, GEnothera, Clarkia, Ludwigia, Bar- 

 tonia, Claytonia, Heuchera, Itea, Hamamelis, Mitchella, Aster, Solidago, 

 Liatris, Rudbeckia, Gaillardia, Vaccinium, Andromeda, Kalmia, Sabbatia, 

 Houstonia, Hydrophyllum, Phlox, Monarda, Dodecatheon, Dirca, Hamil- 

 tonia, Lewisia, Trillium, Medeola. 



Predominant trees and shrubs. Pinus Strobus, P. inops, P. resinosa, P. 



