410 M. De Candolle on the Geography of Plants. [June, 



which this remark applies is so considerable, as not to render 

 it necessary to adduce any more particular illustrations. It is to 

 be observed that the above examples are all taken from plants 

 with conspicuous organs of fructification, the identity of which 

 it is more easy to ascertain ; if the cryptogamia be taken into 

 account, the observation will apply still more generally. 



3. Among those plants which cannot endure a temperature 

 that is either too high or too low, we observe that when they 

 grow in different latitudes, it is at such heights that the effect of 

 the elevation may compensate that of the latitude. Thus many 

 plants of the Alps and the Pyrenees grow in the plains of the 

 north of France ; and, on the contrary, the Lapland plants, when 

 they giow in France, are found on the mountains. The saxi- 

 fraga groenlandica grows on the Pyrenees, at an elevation of 

 from 3,278 to 2,400 metres above the level of the sea ; the Linnaea 

 borealis is not found in the Alps at a height less than from 

 1,800 to 2,000 metres. The chesnut flourishes in the plains of 

 the north of France, on the hills in the south of France, and 

 ascend to a considerable height on the Appennines and on 

 iEtna. 



4. Plants which are cultivated on a great scale obey laws 

 entirely corresponding to the above ; those which vegetate in all 

 latitudes vegetate also at all heights. M. Humboldt informs us 

 that the potatoe, which flourishes so well in our northern conti- 

 nents, is cultivated in Chili at a height of 3,600 metres. The 

 same kind of remarks may be made upon the different species of 

 grain, and they may be likewise extended to those plants which 

 are more impatient of cold. The highest point in which maize 

 is regularly cultivated is above the village of Lencans, in the 

 department of the Lower Pyrenees, at a height of about 1,000 

 metres. Setting out from this point, which is in the 43d degree 

 of latitude, and going 5° north, we come to the neighbourhood 

 of Mans, the most northerly part where maize is cultivated. 

 The same observations may be made upon the vine, the fig, and 

 the olive ; and from all the facts, both those that refer to wild, 

 and those that, refer to cultivated plants, we arrive at the same 

 conclusion, that such as have limits relative to a mean temper-* 

 ature, have them equally in latitude and in elevation ; and that, 

 on the contrary, such as grow almost equally well at all temper- 

 atures, are found in all latitudes and at all heights. 



Although these facts prove that the influence of temperature 

 is very considerable, yet it has been observed that the mean 

 temperature is by no means a correct guide for us to follow in 

 the appreciation of the effects of climate upon vegetation. But 

 it is to be remarked that the distribution of the heat in the differ- 

 ent seasons of the year has a very powerful effect upon the life 

 of vegetables, and, consequently, upon their geography. We 

 know that absolute elevation produces upon the distribution of 

 the mean heat an effect analogous to distance from the equator; 

 thus the nearer we are to the equator, or to the level of the sea, 



