BOTANY OF THE CEYLON PATANAS. . 307 
Area of the Patanas. 
The area of the patanas is not known with any degree of 
accuracy. Tennent almost certainly exaggerates when he says 
“the extent of this patana-land is enormous in Ceylon, amount- 
ing to millions of acres ” (11). The area of the district under 
consideration may be taken roughly as 300 square miles. 
Theories to account for the Origin of the Patanas. 
The existence of extensive, comparatively barren, patana-areas 
in the midst of the luxuriant sub-tropical growth of the montane 
region, and, more particularly, the manner in whieh they abut 
upon the boundaries of the western forests, have attracted the 
attention of many observers. To account for the existence in 
such close proximity of two floras so widely different, three 
theories have been advanced. 
(1.) Trimen’s Theory. 
Trimen, in the paper referred to (12), does not attempt a 
general explanation of the causes which have been active in 
the selection of the forms which now compose the flora of the 
patanas. He gives, however, his opinion respecting the main- 
tenance of a definite line of separation between the western 
boundary of the patanas and the forest. He says that “in the 
course of vast ages a perfect equilibrium between the two floras 
(i.e. patana and forest) has been arrived at, so that now, neither 
ean encroach on the other: the patana-plants are unable to 
exist in the dense shady forest, whilst the seeds of the forest- 
trees never get a chance even of germination in tne closely- 
occupied grass-land. So far as ean be observed, this balance is 
now maintained without change.’ It must, however, be im- 
possible that a line of separation such as is here indicated, not 
only definite but also fixed, could be maintained in nature, unless 
it were determined by some sharp physical barrier, impassable to 
the plants on either side of it. That such a barrier is wanting 
here is obvious to anyone who follows the forest-edge for a short 
distance. But, apart from this theoretical consideration, it is by 
no means difficult to find seedlings of forest-trees establishing 
themselves among the patana-grasses ; and, further, not a few 
of the characteristic patana shrubs and herbs are commonly 
found in the dense shady forest. The experience of foresters 
