RELATION BETWEEN CLIMATE AND VEGETATION. 191 



free, it, in Diervilla, adheres to tlie corolla ; and in Diervilla the 

 corolla is irregular and gibbous on one side at the base, while 

 in Weigela it is regular and equal-sided at the base. 



John Lindley. 



XXIX. — Contributions to a History of the] Relation between 

 Climate and Vegetatio7i in various parts of the Globe. 



No. 1. — The Vegetation of Rio Janeiro. By George Gardner, 

 Esq., F.L.S., Director of the Eoyal Botanic Garden, Ceylon. 



There is perhaps, no part of the world where, in an equal ex- 

 tent of country, a greater variety of vegetable forms are to be 

 met with than in the province of Rio de Janeiro ; and it is quite 

 certain that none of the other Brazilian provinces can be at all 

 compared with it. Situated on the verge of the Southern Tropic, 

 and consisting principally of deep valleys and high mountain 

 ranges, some of which reach to an elevation of nearly 7000 feet 

 above the level of the sea, it necessarily presents a variety of soils 

 and situations favourable to different races of plants, and pos- 

 sesses the two great requisites indispensable for their growth ^ — 

 heat and moisture. The neighbourhood of Rio itself has been 

 oftener visited by botanists than any other part of the empire ; 

 but its botanical riches are even now far from being exhausted. The 

 first five months of my residence in the country were devoted to 

 the investigation of this district, and having worked up my col- 

 lections since my return to England, I found them to contain about 

 20 per cent, of new species ; but as an eternal spring and sum- 

 mer reign in this happy climate, and as every plant has its own 

 season for the production of its flowers, every month is charac- 

 terised by a different flora ; and it can scarcely be expected that 

 the whole of its treasures should be made known for a long time 

 to come. 



The country round Rio is essentiallj'^ granitic ; and the soil, 

 which is highly argillaceous, has been principally formed by the 

 decomposition of such rocks. It is of a red colour, very tena- 

 cious when wet, and is often from 30 to 40 feet in thickness. It 

 is only in the valleys that an alluvial soil covers this to any 

 depth ; for on the mountain declivities it is seldom more than 

 half a foot in thickness. This is no doubt caused by the heavy 

 rains washing it, as well as the materials of which it is formed, 

 down into the valleys. The rainy season sets in about October, 

 and lasts till April or May ; but from the vicinity of the moun- 

 tains, and of the vast forests by which they are covered, showers 

 fall nearly all the year round. It has been remarked, however. 



