CAROLINIAN AREA IN ALABAMA, 57 
advanced to furnish the data required for this purpose. The frequent 
yet only indistinctly perceived overlapping of these zones adds to the 
difficulty of placing satisfactorily the lines by which they are separated. 
The efforts here made to lay down the lines of life zones and their 
subdivisions can only be regarded as tentative. 
The following subdivisions of the life zones of Alabama have been 
recognized as floral regions; that is, as endowed with a flora of 
characteristic and distinct features, due to the presence of types 
which, if not confined exclusively to their limits, predominate within 
them and impart a peculiar character to their several associations. 
The prevalence of one or another of these associations or plant forma- 
tions in the different sections of the same region determines the 
character of its subordinate floral divisions. 
CAROLINIAN AREA OR FLORA. 
A line drawn from the northwestern corner of the State to the lower 
part of Lee County, crossing the Coosa Valley near Childersburg; makes 
the limit of the highlands having an average elevation of 800 feet above 
sea level (KE. A. Smith). This line coincides approximately with the 
isothermal line of 60° F., and may be regarded as the boundary in Ala- 
bama of the Upper and Lower Austral zones, therefore of the Carolin- 
ian and Austroriparian or Louisianian areas. It winds its way from 
norihwest to southeast and southward to the ‘fall line.” Accepting 
this zonal line, a botanical limit is gained, northward of which is found 
a flora different in character from that to the southward, generally 
described as the flora of the great Central Mississippi Valley, and dis- 
tinguished by the feeble representation, if not total absence, of the 
subtropical element and the exclusive prevalence of deciduous forests. 
Various shrubs and trees coincide in their limits of northern and south- 
ern distribution closely with this boundary line, and serve as unerring 
guides in pointing out its course. Such truly zonal plants are: 
Pinus virginiana (scrub pine). Prunus americana (American plum). 
Quercus acuminata (yellow-bark chest- Azalea arborescens (sweet-scented azalea). 
nut oak) . Stuartia pentagyna (fringed stuartia) . 
Quercus prinus (mountain oak). Butneria fertilis (mountain spicewood or 
Quercus coccinea (scarlet oak). smooth calycanthus). 
Quercus rubra (red oak) . Rhus aromatica (aromatic sumac) . 
Acer leucoderme (white-bark sugar maple). -Adelia ligustrina (southern privet). 
These all find in Alabama their southern limit on this line. Although 
the vegetation of the Carolinian area presents in its broad features great 
uniformity, particularly in its tree growth, there exist in its range of 
nine degrees of latitude differences in the latitudinal distribution of 
heat, which necessarily affect the distribution of plants within its lim- 
its and present insurmountable obstacles to the extension of a number of 
species northward. Due to this temperature element, there is a most 
pronounced limit beyond which the successful cultivation of the cotton 
