Page:The Journal of Indian Botany.djvu/185

 pass. The Inner Himalayas have been crossed only at one place, the Baralacha pass (16,200 ft.). The country beyond that has been visited for about twenty miles up to Lingti Sumdo but the climatic conditions on that side are so uniform over large areas that nothing new would probably be found even much further inwards. The minimum elevation of this region ia 14,000 ft. In all cases the forms collected most were from the road-side along the rivers at different levels and at various levels during the crossing of the ranges though short excursions were also often made away from the main road.

General Results.

The more important general conclusions may be stated briefly as follows : —

Most of the species found in the Western Himalayas are thallose.

In the Outer Himalayas the number of species found at a given altitude decreases in proceeding from the eastern end to the west. This decrease is very much more marked if we take into consideration the number of individuals. (Vide lists of species at the end.)

As regards vertical distribution, the number increases up to a certain height in going from the plains. The number in the plains is very small. It increases up to about 7,000 ft. and begins to decrease again after that. This applies also to the number of individuals. (Vide lists of species at the end.)

On the northern side of the Outer range the same law holds good but the number of species and individuals is much smaller. Thallose forms are chiefly found only near springs. In other places they are as a rule absent.

The horizontal distribution in the Ravi valley probably follows the rule given above but the data are too few to admit of a definite statement being made. (Vide list.)

On the southern side of the Middle Himalayas the number is even smaller than on the northern side of the Outer range, and it decreases as we go up.

In the Chandrabhaga valley it can be definitely stated that the number decreases as we go down the river. The number on both sides of the river is very small, but of the two the left bank, i.e., the northern slope of the Middle range is comparatively richer. Pangi is the only part where any foliose forms have been met with. They are absent both to the east and west of it.

The initial level of this valley is very high, being above 8,000 ft. in the Chamba territory. The largest number of individuals is met with between 8,000 and -9,000 ft. in Pangi and up to 11,000 ft. in British Lahoul. The explanation of this difference no doubt lies