Se 
1903] FLORA OF NORTH CAROLINA 379 
SUB-ALPINE DWARF TREE-SHRUB FORMATION. 
This formation may be said to exist only at the top of Grand- 
father Mountain and is absent from the domes and ranges of 
Mount Mitchell and Roan Mountain. 
The summit of the west peak of Grandfather Mountain for a 
limited area is bare and presents an alpine aspect, being clothed 
with lichens, mosses, and dense cushions of Dendrium buxifolium 
(Dendrium Association). Several of the plants remind the bot- 
anist of the New Jersey pine barrens, viz., Gaultheria procum- 
bens, Xerophyllum asphodelioides, Pteridium aquilinum, Kalmia 
latifolia. ~ 
Zygadenus leimanthoides, Geum radiatum, Paronychia argyro- 
coma, Uvularia puberula, Clintonia borealis, Carex aestivalis, 
Chrosperma muscaetoxicum, and Solidago spithamea are found 
in exposed places (thus under edaphic conditions) ( Geum-Paro- 
nychia Association). Abies Fraseri, Picea mariana, Clethra acu- 
minata, Sorbus americana, Leucothoe recurva, Vaccinium pallidum, 
Oxycoccus erythrocarpus accompany the herbs to the mountain 
summit, so that this summit may be said not to be entirely tree- 
less, otherwise the plants on it would be classed as an association 
of the Sub-alpine Treeless Formation. 
The presence of Dendrim buxifolium, Xerophyllum asphode- 
lioides, a pine barren species found plentifully in New Jersey, 
Geum radiatum, Paronychia argyrocoma, Clintonia borealis, and 
Chrosperma muscaetoxicum needs explanation. Paronychia argy- 
rocoma, found on the bare mountain slopes of the White Moun- 
tains and in the Alleghenies from Virginia to Georgia and also in 
Maine, and Clintonia borealis are probably species of north tem- 
perate habit that were formerly more widely distributed but have 
been separated into distinct areas by the influence of the base- 
leveling operations previously described. 
The geographic distribution of Xerophyllum asphodelioides 
and Chrosperma muscaetoxicum is probably to be accounted for 
in the same manner as the distribution of the austro-riparian 
Species that occur in the southern Appalachians. It is hardly 
likely that the seeds of these plants were carried to the summit 
of the few isolated peaks by birds, because one would expect to 
