NORTHERN PLANTS REACHING THE DISMAL SWAMP. 449 



of the vegetation, are properly Austroriparian plants. Among these 

 "character plants" are a considerable number which do not extend 

 north of the Dismal Swamp region, namely: 



Finns palustris. Zanthoxylum clava-herculis. 



*Erianthus saccharides. Jatropha stimulosa. 



*Panicum gibbum? Berchemia scandens. 



* Uniola panicula ta . Cornus stricta . 



Arundinaria macrosperma. Nyssa aquatica. 



*Cyperus haspan. Nyssa biflora. 



*Fimbristylis spadicea. Leucothoe axillaris. 



Cladium effusum. *Pieris nitida. 



Carex verrucosa. Styrax grandifolia. 



*Tillandsia usneoides. *Fraxinus caroliniana. 



Atamosco (Zephyratdhes) atamasco. Gelsemium sempervirens. 



Q aercus laurifolia. Callicarpa americana. ' 



*Quercus virginiana. *Physalis viscosa. 



Clematis crispa. Bignonia crucigera. ] 



Persea borbonia. *Eupatorium capillifolium. 



Persea pubesce i is. *Borrichia frutescens. 



*Decumaria barbara. ' 



Those species whose names arc preceded by an asterisk (*) are not 

 confined to the Lower Austral zone, but extend southward into the 

 tropical region. A complete list of the species which are known to 

 reach their northern limit in the Dismal Swamp region is given in 

 the table of northern limits of Austroriparian species, which will be 

 found at the end of this chapter. 



PLANTS REACHING THEIR SOUTHERN LIMIT IN THE DISMAL SWAMP 



REGION. 



Besides the Lower Austral element which dominates the flora of 

 this region and the large number of Upper Austral species, there are 

 a number of plants which apparently here reach their southern limit, 

 at least in the Coastal plain. These belong to three categories: (1) 

 Strand plants hardly to be reckoned to any of the life zones; (2) 

 mostly palustrine species, chiefly of boreal origin, to which the cold, 

 wet soil of the swamps offers a congenial environment; and (3) non- 

 palustrine species, which are either of the Transition zone or of 

 both that and the Upper Austral. A prefixed (*) indicates that the 

 species reaches its actual austral limit in point of latitude, irrespective 

 of altitude, in the Dismal Swamp region. 



1. STRAND PLANTS. 



*Ammophtia arena ria. * *Ammodenia peploides. 



* Festuca rubra. :i * Hudsonia tomentosa. 



* Lechea maritima. 4 



1 Occurs sparingly in mountain valleys in eastern Tennessee. 



2 Ranges several miles south of Virginia Beach and perhaps into North Carolina. 

 :; The var. glau cescens Hack, occurs in central Tennessee. 



4 Accredited by Watson to Georgia, but this requires confirmation. 



