280 
THE PLANT WORLD. 
blueberry), arising from a mossy bed beneath the balsams, is a 
shrub from a foot to two feet high, and its position in the dense 
shade indicates the fact that on many of the mountain summits 
now denuded of their timber the blueberry thickets have been 
derived from shade-growing species of Vactinium, that have 
adapted themselves to the changed environment. At lower eleva¬ 
tions in this formation, one finds Rhododendron ( Azalea ) viscosa, 
and R. nudidorum. On Slide Mountain at an elevation of 3,500 
feet on cliffs and ledges under the balsams, Abies balsamea, were 
collected such mosses as Raphidostegium Jamesii, R. laxepatu- 
lum, Plagiothecium striatellum, P . Mullerianum, Hylocomium 
umbratum, H. Pyrenaicum, Dicranum fusescens and D. longi- 
folium. 
The balsam formation covers only the highest mountain peaks 
in the Catskills, viz., Wittenberg (3,824 feet), Table Mountain 
(3,875 feet), Cornell (3,920 feet) and Slide Mountain (4,220 
feet), the latter the highest summit in the Catskills. It extends 
down the mountain slopes in tongues into the deciduous forest 
below and at lower elevations, it breaks up into isolated patches, 
easily delimited by the dark green color in a lighter green back¬ 
ground. Its constitution is very similar to the topmost plant 
formations in the Adirondack mountains and in the mountains of 
Virginia, North Carolina and Tennessee.* 
Rocky Ledge Plant Formation. This formation is found on 
the rocky ledges and bluffs which occur throughout the Catskill 
mountains. The plants, which characterize such ledges, are 
mainly the ferns: Camptosorus rhizophyllus, Pellaea gracilis, 
Woodsia ilvensis, Asplenium trichomanes, Poly podium vulgare, 
and a few herbs, Saxifraga virginiana, Arabis lyrata (rock 
cress) ; Aquilegia canadensis (columbine) ; Heuchera americana 
(alum-root) ; Polygonum cilinode, Campanula rotundifolia (hare¬ 
bell), and various species of lichens, as of the genus Umbilicaria, 
and the blue green alga, Nostoc sp. 
* Harshberger, John W. An ecological Study of the Flora of Moun¬ 
tainous North Carolina. Botanical Gazette 36: 376-381; Harshberger, 
John W. The Plant Formations of the Adirondack Mountains. Torreya 
V: 187-194. 
