420 
AMEEICAW RlIODODENDKOirS. 
having an analogous climate. Such, are the general pheno- 
mena of the distribution of plants. 
It is now said that a mountain is high enough to enter 
into the limits of the rhododendrons and the befarias, as it 
has long been said that such a mountain reached the limit 
of perpetual snow. In using this expression, it is tacitly 
admitted, that under the influence of certain temperatures, 
certain vegetable forms must necessarily be developed. Such 
a supposition, however, taken in all its generality, is not 
strictly accurate. The pines of Mexico are wanting on the 
Cordilleras of Peru. The Silla of Caracas is not covered 
with the oaks which flourish in New Grenada at the.same 
height. . Identity of forms indicates an analogy of climate ; 
but in similar climates the species may be singularly diver- 
sified. 
The charming rhododendron of the Andes (the befaria) was 
first described by M. Mutis, who observed it near Pamplona 
and Santa I e de Bogota, in the fourth and seventh degree of 
north latitude. It was so little known before our expedition 
to the Silla, that it was scarcely to be found m any herbal in 
Europe. The learned editors of the Flora of Peru had even 
described it under another name, that of acunna. In the same 
manner as the rhododendrons of Lapland, Caucasus, and the 
Alps* differ from each other, the two species of befaria we 
brought from the Sillaf are also specifically different from 
that of Santa Fe and Bogota. £ Near the equator the 
rhododendrons of the Andes§ cover the mountains as far 
as the highest paramos, at sixteen and seventeen hundred 
toises of elevation. Advancing northward, on the Silla de 
Caracas, we find them much lower, a little below one thou- 
sand toises. The befaria recently discovered in Florida, in 
latitude 30°, grows even on hills of small elevation. Thus 
in a space of six hundred leagues in latitude, these shrubs 
descend towards the plains in proportion as their distance 
* Rhododendron lapponicum, R. caucasicum, R. ferrudneum, and 
R. hirsutum. 
f Befaria glauca, B, ledifolia. 
t Befaria sestuans, and B. resinosa. 
§ Particularly B. sestuans of Mutis, and two new species of the sout tern 
hemisphere, which we have described under the name of B. coarctata, and 
B. grandiflora. 
