XXXIV 
INTRODUCTION 
It will be seen that in large areas, such as India, Mexico and 
Australia, the number of species to a genus is approximately 
half of what it is in the whole world ; whereas in the small area 
of Simla it is less than a sixth, and in the remote St. Helena it is 
only a twelfth. This is in accord with the general law that the 
floras of small areas and of remote islands are relatively richer 
in Orders and Genera than in Species. But the average number 
of species to a genus is unusually low in Simla for a continental 
area having a luxuriant vegetation. 
In my recent paper on the Flora of Tibet 1 I obtained the 
following figures : — 
Regions 
Orders 
Genera 
Species 
Himalaya, from 15,000 ft. 
and upwards 
38 
149 
470 
Tibet ' . 
! 
41 
119 
283 
THE TREES OF SIMLA 
The woody element largely predominates in the vegetation of 
Simla, and the following species attain the dimensions and character 
of trees, though some of them are shrubby in certain localities : — 
Bixacece 
Flacourtia sapida. 
Xylosma longifolia. 
Malvaceae 
Bombax malabaricum. 
Tiliacece 
Grewia oppositifolia. 
vestita. 
Rutacece 
Murray a Koenigii. 
Limonia acidissima. 
iEgle Marmelos. 
Meliaceoe 
Melia Azedarach. 
indica. 
Cedrela serrata. 
Toona. 
Aquifoliacece 
Ilex dipyrena. 
odorata. 
Celastracece 
Euonymus Hamiltonianus. 
lacerus. 
pendulus. 
tingens. 
Elseodendron glaucum. 
1 Journal of the Linnean Society, xxxv. p. 230. 
