10 THE OAK-VEGETATION OF AMERICA. 
- — Alexander von Humboldt has placed the lower limits of the Oaks on 
the eastern coast of Mexico, at 400 toises, or 2400 feet; an assertion 
which proves, how precarious it is, to draw general conclusions from in- 
adequate data. Since Humbo!dt, during his journey in Mexico, became 
acquainted with the state of vegetation on the eastern slope of the Cor- 
dilleras, by one single route only, from Jalapa to Vera Cruz, his state- 
ment should, in justice, be applied. exclusively to that line, and not 
be extended beyond; for then it will be found incorrect. And yet has 
this Humboldtian view of the lowest limit of the Mexican Oaks, on 
- the east side of the Cordilleras, been repeatedly quoted, as an undoubted 
fact, which it cannot be, unless expressly limited in the manner which we 
have indicated ; because both north and south of that line Oak-forests 
are met with, down to the very coast in the Department or State of 
Vera Cruz. It is Q. oleoides which thus extends to the very coast; a 
- handsome, not very large tree, growing in clumps, and forming small 
. groves on the savanas, rarely small forests. These savana-groves possess 
much picturesque beauty, by breaking the monotony of the extensive 
grass plains. The tree has shining leathery leaves; the stem and 
branches are mostly covered by masses of parasites with magnificent 
flowers, such as Orchidesm, Tillandsiz, Pipera, Visca, and Loranthi. 
Among the first we may name the splendid Schomburgkia tibicina, many 
fine Epidendra, Oncidia, Mazillaria, etc.; while the known grey-bearded 
Tillandsia usneoides hangs down from the branches and wafts its deli- 
cate fibres to the winds. 
— As it rises imperceptibly from the shore, the country produces, at an 
elevation of 2-3000 feet, an increased number of Oak species: small 
trees with stiff, mostly woolly leaves, forming small open forests on 
the low ridges or margins of the deep volcanic ravines, which intersect 
the east coast. They disappear in low situations, fertilized by the soil 
which has been washed down, and also in the barraukas, or ravines, 
where, with a want of light, there exists likewise too great moisture.. 
3 characterizing this belt we may name Q. petiolaris, tomentosa, and 
The Oaks at an elevation of 3000 feet become loftier and more 
stately; they form dense forests, and increase considerably in the 
E: number of species. Here the heat becomes already more temperate 
ar C. mean temperature), and the fall of rain is great; the climate 
is the finest one can desire. It is concerning this portion of the region 
