BOTANY OF THE CEYLON PATANAS. 305 
here than at lower elevations: e. g., Knoxia platycarpa, Vernonia 
Wightiana, Atylosia Candollei, Osbeckia sp., ete. Other shrubs 
which hardly occur below 5000 fect are Hedyotis Lawsonie, 
Hypericum mysorense, Blumea sp., Rubus sp., ete. Several 
species of ground Orchids are almost confiued to elevations 
above 5000 feet; and hardly less so are two or three species of 
Exacum, whose bright blue flowers are the chief ornament of 
the patanas above 5000 feet; while species of Wahlenbergia, 
Crotalaria, Cassia, and Anaphalis have a wider range. 
The Western Boundary of the Patanas. 
Where the patanas come into contact with the western forest, 
the boundary lines are remarkably sharp and abrupt, though 
quite irregular and in no way related to any physical features 
of the land. The ordinary forest-growth is found within 3 to 
6 feet of the normal patana-vegetation, only a very narrow 
belt intervening. The plants composing this intermediate belt 
consist principally of stunted forest-trees and such of the forest 
undershrubs as are fouud also on the patanas, as well as other 
shrubby species which are more particularly characteristie of the 
patanas; with these are mingled comparatively few of the 
coarser patana-grasses, conspicuous among which is the tall 
aromatic “ Mana "-grass (Andropogon Nardus). | Occasionally 
the belt is alinost entirely composed of a single shrubby species, 
such as Hedyotis Lawsonie or Knoxia platycarpa. The forest- 
edge thus presents a sloping-wall of foliage which rises abruptly 
from the low grassy vegetation of the patanas to the height of 
the forest-trees. 
The first impression gained from an examination of the flora 
of this narrow intervening belt, is that the causes which have 
determined its composition are artificial rather than natural. It 
differs markedly in its constitution from the intermediate flora 
found between the American prairies and the adjoining forest, 
which, if Macmillan’s view of the latter is correct (8), consists 
of “species weaker than the characteristic plants of either 
formation.” He states that, in the struggle tor existence, the 
weaker species of the prairie and the forest respectively are 
crowded to the common periphery of the two formations, and 
there mingle, thus constituting a flora intermediate between the 
two which it separates. 
