576 ZONES AND REGIONS [Pt. Ill, Sect. II 



The vegetation is very varied in the swamps, which extend over thousands of 

 kilometers in North Carolina (Dismal Swamps, Wilmington Swamps). The appear- 

 ance presented by the forest varies according to the physical and chemical nature of 

 the soil, and according to whether this is annualty flooded for a longer or a shorter 

 period. Wet loamy soil that is flooded, however, only in spring, becomes 'oak 

 flats,' where various deciduous oaks, poplars, maples, and the like, form forests up 

 to iooft. in height ; and in their shade, small trees thrive as an underwood (Quercus 

 minor, Carpinus caroliniana, Crataegus). In the lowest places, that are always inun- 

 dated or only superficially dry, Taxodium distichum and Liquidambar styraciflora, 

 together with a few other subordinate trees, form the swamp forest. On sandy and 

 peaty soil, forming an essential part of the Dismal Swamps, forests of Cupressus 

 thyoides prevail, in which broad-leaved trees, such as the tulip-tree, Liquidambar, 

 Persea Borbonia, occur scattered about, and where the richly humous soil between 

 the trunks is often completely covered by sphagnum. On very sterile soil in the 

 Dismal Swamps, Pinus serotina predominates, and equalling Pinus palustris in its 

 accommodating nature, replaces the latter on wet soil. These pine-woods are thin 

 and are rich in shrubby underwood. 



The forests on the outlying hills form a transition between those of the low-lying 

 coast-land and those of the mountains. On soft, permeable, moist soil there are 

 deciduous broad-leaved forests, in which oaks and species of Carya predominate, 

 whilst on sandy soil pines (Pinus mitis, P. Taeda) form the overgrowth. 



In the mountains differences in soil are less effective than in the lowlands, but so 

 much the more effective are differences in temperature and rainfall. The mountain 

 forests display the greatest luxuriance on the northern humid slopes, whilst the 

 southern slopes exhibit more open woods, especially of light-demanding species. 

 At altitudes between 1,500 ft. and 3,000 ft., these forests consist of pines and broad- 

 leaved trees; the latter are usually somewhat overtopped by the former (Fig. 318). 

 The pines are chiefly Pinus Strobus, often 100-150 ft. high, P. mitis, P. rigida, 

 P. pungens ; the broad-leaved trees, that occasionally attain a height of 90 ft., are oaks 

 (Quercus alba, Q. Prinus, Q. tinctoria, Q. coccinea, Q. rubra, Q. imbricaria), chestnuts 

 (Castanea vesca, var. americana), species of Carya, Cornus florida. The broad-leaved 

 trees become the more plentiful the moister and the more fertile is the soil. In 

 less dense woods two evergreen ericaceous plants, Rhododendron maximum and 

 Kalmia latifolia, form dense thickets between the trunks. 



The grandest forests of the Southern Alleghanies, and those that have best 

 preserved their original character, occupy the region between 3,000 ft. and 5,000 ft. 

 (Fig. 319). Their finest development occurs on the moist northern slopes rich in 

 humus. Only one conifer, Tsuga canadensis, is usually found in these forests ; 

 otherwise they consist of a profusion of broad-leaved trees : birches, maples, beeches, 

 chestnuts, oaks (Quercus rubra, Q. alba). The tulip-tree, Fraxinus americana, Mag- 

 nolia acuminata, Aesculus flava, grow mingled together ; the highest crowns form 

 a continuous dense leaf-canopy, 90-120 ft. high, beneath which and near their mother- 

 plants young individuals of tall trees often flourish, whilst other places are covered 

 by dense evergreen shrubs of Rhododendron maximum and Kalmia latifolia. 



Above this forest level the broad-leaved forest is replaced by a coniferous forest of 

 Picea nigra and Abies Fraseri. 



