376 BOTANICAL GAZETTE [NOVEMBER 
dominant species are Quercus rubra, Picea mariana, Acer sac- 
charinum, Prunus pennsylvanicum on the drier soils, and Tsuga 
canadensis ( 7suga Association) ascending along the water courses 
to about 4,700" (1,430™). Thesecondary species are Acer penn- 
sylvanicum, Sorbus americana, Viburnum alnifolium, and Acer 
spicatum (Acer-Sorbus-Viburnum Association). The herbaceous 
plants of this part of the mountain have more light and comprise 
Osmunda cinnamomea, Pteridium aquilinum, Polygonum cilinode, 
Houstonia_ serpyllifolia, Podophyllum peltatum, Lysimachia 
quadrifolia, Saxifraga Michauxii, Rumex acetosella, and Chrysan- 
themum leucanthemum. Occurring as undershrubs are Rhodo- 
dendron lutea, Ribes rotundifolium, and Viburnum alnifolium. 
On Roan Mountain the first indication of rise in altitude is 
furnished by Acer spicatum, and then by Acer pennsylvanicum, 
which does not descend quite so low as the mountain maple. 
Viburnum alnifolium occurs in great abundance when at an alti- 
tude of 4,500* (1,370™) is reached. Houstonia serpyllifolia 
carpets the ground in many places, while in damp places 
Diphylleia cymosa forms masses beneath the shade of the domi- 
nant forest trees. The herbaceous plants of the forest floor at 
this elevation are Caulophyllum thalictroides, Actaea alba, 
Cicimifuga racemosa, Tiarella cordifolia, Sanguinaria canadensis, 
Podophyllum peltatum, Circaea alpina, Blephariglottis peramoena, 
Cacalia atriplicifolia, Lysias orbiculata, Chelone Lyoni, and Poly- 
stichum acrostichoides. A few straggling black spruce trees 
descend the mountain side and mingle with Betula lutea and B. 
lenta. Fagus americana, which becomes dwarfed at the edge of 
the coniferous belt, is associated with the birches in this tension 
zone (Betula-Fagus Association). 
Aesculus octandra, which occurs at the upper edge of the 
tension zone, ascends the mountain into Carver’s Gap, where it 
forms an almost pure stand of gnarled trees (Aesculus Association). 
CONIFEROUS FOREST FORMATION. 
The coniferous forest appears on the slopes of the Black 
Mountain Range at about 5,200 (1,585™). The dominant tree 
of this formation is Picea mariana, associated with Abies Fraseri. 
Intermingled with these two coniferous trees, but nowhere mak- 
