1818.] M. Be Candolle on the Geography of Plants. 413 



whilst it loses its importance as we approach the poles. 4. The 

 annual phases of the temperature, as well as the intensity of the 

 light and the dryness, establish a strong relation between the 

 vegetation of very elevated districts and that of the northern 

 countries. 5. Annual and biennial plants, or to speak more 

 correctly, those which fructify only once, become more rare in 

 proportion as we remove from the equator, or from the level of the 

 sea. In our climates there are veiy few which are elevated above 

 1,200 metres. 6. If we proceed upon the estimate, that in our 

 climate 180 to 200 metres of absolute height affect the mean 

 temperature almost in the same manner with a degree of latitude, 

 we shall be able to fix the corresponding limits of vegetables in 

 the scale of heights and in that of latitudes. 



To the memoir are subjoined four tables, containing lists of 

 the plants that are found in France, arranged according to the 

 heights at which they grow. In the first, we have the plants 

 which are never found in France below 2,000'metres of absolute 

 height ; in the second, those which are only found in France 

 between 1,000 and 2,000 metres of absolute height ; in the 

 third, those which grow in France indifferently above 1,000 or 

 2,000 metres of height, but not below ; and in the fourth, the 

 plants which grow in France indifferently below and above 1,000 

 metres, omitting those the difference of which between the 

 minimum and the maximum does not equal 1,000 metres. In 

 all these lists there are no cryptogamian plants admitted. The 

 results that may be collected from these tables are as follows : 

 The first table contains 60 species all perennial ; the second, 206 

 species all perennial; the third, 15*3 species; the fourth, 517 

 species. From these tables, besides the cryptogamian plants, 

 which in France amount to 1,500 species, are excluded 700 

 annual plants, which, for reasons mentioned above, can only 

 grow in places where the snow lies for a considerable length of 

 time ; 300 marine plants, which, having a necessity for salt water, 

 cannot grow except on the sea coast, or in salt marshes ; about 

 800 plants, which, requiring a certain degree of warmth, cannot 

 grow in the plains of the north, or in the mountains of France : 

 and, lastly, about 300 species, which are too rare or too little 

 known to enable us to affirm any thing with certainty concerning 

 them. There remains about 1,500 species, which grow in all 

 situations indifferently, making up a total of 5,000 that are 

 indigenous in France. 



