298 
mFLUENCE OF CLIMATE ON VEGETATION. 
This table is, of course, arbitrary ; but a few illustrations will show that it approximates 
to the truth. Thus, for example : — Bogota, in New Grenada, lies within the parallels of 
80° — 85° mean annual temperature, and has an elevation of 8100 feet; in the column 
headed 85°, 7600 feet (which is within 500 feet of the altitude of Bogota), will be found to 
range opposite to 60° in the left-hand column of temperatures ; the mean annual tempe- 
rature of Bogota is recorded to be 59°-f. 
Kandy, in Ceylon, lies about the parallel 80° mean annual temperature, and has 
an elevation of 1790; in the table under 80°, 1520 feet, (the nearest to 1790) stands 
opposite 75° ; while the mean annual temperature of Kandy is actually 72° -f. 
Darjeeling, in the East Indies, lies within the parallel of 72° — 75° mean annual 
temperature, and has an elevation of 7414. The table shows 50°, opposite to 7600 
feet in the column headed 75°; the recorded mean annual temperature of Darjeeling 
being 56°. 
Perth, in Western Australia, lies wdthin the parallels of 65° — 70° mean annual tempera- 
ture ; and being unaffected by altitude, we find the actual mean annual temperature of 
Perth to be 67° -f. What cool treatment we give our Swan Kiver plants I 
Funchal, in Madeira, lies within the parallel of 55° — 68° mean annual temperature 
and is 80 feet above the sea ; in the table 65° is found opposite 0° in the column headed 
65° : the mean annual temperature of Funchal being 67°+ . 
Neufchatel, in Switzerland, lies about the parallel 55° mean annual temperature, and 
has an elevation of 1438 feet. The table shows 50° opposite 1520 feet in the column 
headed 55° ; the mean temperature of Neufchatel being 51° + . 
^tna, in Sicily, lies about the parallel 65° mean annual temperature, and has an eleva- 
vation of 9807 feet. In the table, 9120, under 65°, is seen to indicate 32° ; while the 
mean annual temperature of ^tna, 700 feet higher, is actually 29° + . 
It is thus pretty evident, that with the aid of a map of isothermal lines, -i' and a table 
constructed on some such plan as the foregoing, it would be easy to arrive at an 
approximate knowledge of the mean annual temperature of any part of the globe, if its 
elevation be known ; and consequently, any person receiving seeds or plants from foreign 
parts, if informed of the country whence they come, and the elevation, might by an easy 
process, learn what it is most material to know, as to the artificial temperature proper for 
their cultivation. 
But, in order to show that Botanical Geography is no trifling or simple study, it may 
be mentioned that the same species of plant is in the majority of cases distributed over 
a greater or less extent of the earth's surface ; and may be thus found in positions where 
both the annual mean temperature and the altitude are materially different. To judge, 
therefore, what temperature is best suited for any given plant, it is necessary to know 
within what limits it is thus naturally dispersed, and its geographical range having been 
ascertained, the climatic differences indicated (if any) must be duly balanced. 
There are many other matters to be taken into account in estimating the influences of 
climate on vegetation. Some of the principal of these are — sun-light, density or rarefaction 
of the atmosphere, and moisture. The two first are in a measure uncontrollable by 
cultivators ; and hence arises many of the difficulties of cultivation, as well as many of 
its failures. There are items, however, in the sum total of the climate of particular places, 
which it is important to know, in order to imitate them as far as may be possible. With 
moisture it is different ; this may be limited or increased, and that to such an extent, that 
moisture and temperature are verily looked upon, in no paucity of instances, as the only 
elements of climate. 
The cultural groups indicated in the former part of these remarks were founded on 
temperature alone. Taking moisture, also, into account, most of these groups will require 
dividing into two to suit the purposes of the cultivator, according as the plants require 
a greater or less degree of atmospheric moisture. This is not merely the case with those 
plants on the one hand, which require an arid atmosphere ; and on the other, those which 
* Such a map, on a small scale, is published in Part VI. of the « Physical Atlas," small edition. 
London and Edinburgh, Blackwood. 
