NOVEMBKE 30, 1900.] 



SCIENCE. 



831 



Potentilla tridentata, and Trisetum subipieatum, 

 may be regarded as typical of this zone. 



By far the greatest part of the surface of 

 the mountain region is covered with an 

 Alleghanian (Transition) flora. To this 

 zone may be reckoned such woody species 

 as the cherry birch {Betula lento), species of 

 Magnolia {Umbrella, acuminata, Fraseri), 

 sugar maple (Acer saccharum') , the big laurel 

 {Rhododendron maximum), mountain laurel 

 {Kalmia latifolia), etc. Mingled with these 

 are black walnut {Juglans nigra), tulip tree 

 {Liriodendron tulipifera), shag-bark and 

 mocker-nut hickories {Hieoria ovata or 

 Carya alba and H. alba or Carya tomentosa) , 

 white and chestnut oaks ( Quercus alba and 

 Q. Prinus), holly {Ilex opaca), chestnut 

 {Castanea dentata), "witch hazel {Hamamelis 

 virginiana) and beech {Fagua americana, or 

 ferruginea) which are perhaps somewhat 

 more characteristic of the Alleghanian flora, 

 but are hardly less abundant in the Caro- 

 linian. 



The lower slopes of the mountains and 

 the valleys between are largely occupied 

 by extensions of the Upper Austral (Caro- 

 linian) Zone. Very characteristic species, 

 especially along the streams, are button- 

 wood {Platanus occidentalis) , river birch 

 {Betula nigra), linden {Tilia heterophyUa) , 

 hackberry ( Celtis occidentalis) , sweet gum(Xi- 

 quidambar styraciflua) , red mulberry {Morus 

 rubra), 8asBafras(<Sassa/ras officinale), persim- 

 mon {Diospyros virginiana) , tu p elo (iV^yssa syl- 

 vatica) , and species of pine, notably the scrub 

 pine {P. virginiana or inops), and the yellow 

 pine (P. echinata or mitis). Usually inter- 

 mingled with these are numerous partially 

 Transition species, e. g., beech and Amer- 

 ican elm {Ulmus americana). The dried 

 summer slopes add to this list such species 

 as the chinquapin ( Castanea pumila) , sour- 

 wood ( Oxydendrum arboreum) and black-jack 

 oak {Quercus marylandica or nigra) .'* 



*I have purposely omitted from the above lists 

 snoh speoiesasare endemic in tkeSontbern Appalacb- 



Growing amid the often very large body of 

 Carolinian forms, thus established in. the re- 

 gion we are considering, there occurs a much 

 smaller number of species which are most 

 abundant in and characteristic of the Aus- 

 tro-riparian area of the Lower Austral Zone. 

 Only two or three trees and comparatively 

 few shrubs which are distinctly of the Lower 

 rather than the Upper Austral Zone extend 

 into the mountain region. But of herbs 

 the number is a respectable one. Over one 

 hundred species which are most abundant 

 and most widely distributed in the Austro- 

 riparian area are known to occur in the 

 mountains at an elevation of 300 meters 

 (1,000 feet) or more. 



A faint indication of this Lower Austral 

 element is perceptible as far north as West 

 Virginia and southeastern Kentucky; while, 

 on the mostly isolated granitic outcrops in 

 northern central Georgia and northern Ala- 

 bama, of which Stone Mountain is a type, 

 it is so extensive as somewhat to obscure 

 the mainly Carolinian character of the flora. 

 In the former case the Austro- riparian 

 forms are few and unimportant. In the 

 latter instance the stations are so inferior 

 in elevation, are so nearly isolated from the 

 principal mountain chains and are so close 

 to the main borders of the Austro-riparian 

 area as to possess small significance as ex- 

 tensions of that area. Hence we had best 

 confine ourselves here chiefly to that por- 

 tion of the Appalachian Region which falls 

 within the limits of North Carolina and 

 Tennessee. Here we find some of the high- 

 est elevations of eastern North America ; 

 and therefore we are justified in regard- 

 ing as of peculiar interest the presence in 

 their neighborhood of numerous essentially 

 Lower Austral forms of plant life. 



It may be well to limit still further the 

 scope of thepresent investigation by omitting 

 from discussion species which do not reach 



ian Eegion, as being less suitable to indicate the gen- 

 eral zonal relationships. 



