- disappear at the height of 8,670 feet; but 
— the Violet continues to brave the barren- 
- ness of the soil and the drought of the air, 
—— those sudden atmospheric changes that are 
frequently exhibited in the sphere of re- 
action of which the Peak is the centre, 
not appearing to affect its growth; it is 
even found above Altavista, nor is it till 
you reach the small table-land of the Ram- 
bleta that it ceases to be seen. Beyond 
this latter station, the Flowering Plants 
totally fail, the volcano seems to forbid all 
vegetation, a few lichens alone tinging its 
summit; while, at the edge of the crater, 
some minute Mosses ( Weissea verticillata, 
= var. which is seen at 11,424 feet above 
the level of the sea), spring up in the cre- 
vices whence the warm vapours continually 
exhale. 
After this general sketch of the Distri- 
bution of Plants over the lofty region of 
Ténériffe, if we give a glance at the cor- 
responding stations on the adjacent islands, 
we shall perceive that vegetation there 
. Changes its aspect and becomes modified 
. according to the height of the mountains 
.. and the nature of the country. Thus, the 
loftiest summits of the Great Canaria only 
. Attaining 5,842 feet, that is, about half the 
. elevation of the central mountains of Té- 
nériffe, neither the Adenocarpus nor the 
Cytisus of the Peak is to be seen. Still, 
: the summits of Canaria, though destitute 
of arborescent vegetables, do possess their 
alpine plants, which are the representatives 
Valley « of | arde. the Ridge of Manza- 
milla has afforded us also three new spe- 
: cies, Prenanthes pendula (nob.), Sature- 
Ja "cg Ee (nob.), and another 
cimbing plant, which will probably be 
found to belong to the Apocynee. 
Palma has presented us with similar ob- 
servations. According to Mr. Von Buch’s 
ns, the loftiest part of this island 
VEGETATION OF THE CANARY ISLANDS. 
343 
attains a height of 7,234 feet; at this ele- 
vation in Ténériffe, we have already passed 
the limits of the Adenocarpus, and entered 
upon the region of the Cytisus of the Peak, 
yet Palma only possesses the former; its 
soil, both with respect to configuration 
and nature, by diminishing the influence of 
height, preventing the development of the 
latter species. The interior slopes of the 
mountains of Palma form, towards the cen- 
tre of the island, the circumference of a 
primitive crater. When on reaching the 
brink of this fearful gulf, the eye glances 
with alarm down a depth of 4,500 feet, we 
may behold ancient forests starting from 
the enormous crevices which furrow the 
sides of the mountain, while not a shrub 
can be seen on the barren ridges that sur- 
round it. This higher region has an en- 
tirely peculiar character ; it is not, as in | 
Ténériffe, an immense circus, chiefly occu- 
pied by Cytisus, and where the decompo- 
sition of volcanic tufa is favourable to ve- 
getation ; but instead of a central platform 
surrounded by mountains in ruin, a differ- 
ent formation appears, the rocks of Palma 
being of basalt, while those of Ténériffe 
are trachytic. Huge masses of basalt lie 
severed in great blocks, and frowning peaks 
bristle the mountain-tops, and seem actu- 
ally suspended over the abyss. On reach- 
ing these summits, where the compactness 
of the soil limits the growth of the Adeno- 
carpus, and entirely excludes the Cytisus, 
we may find, all along the perilous mar- 
gins, several species that never appear in 
. lower stations; these are the Arabis albida 
of Caucasus, a shrubby variety of De Can- 
dolle’s Cerastium strictum, and Viola 
Palmensis, which here takes the place of 
the Viola cheiranthifolia of the Peak of 
Teyda. Thus the spots that appear most 
utterly barren, often present the Botanist 
with his most valued acquisitions. 
The observations that may be deduced 
from the distribution of plants over the 
Archipelago of the Canaries, rest upon a 
body of highly interesting facts. And when |. 
in investigating the islands in question, we 
scrutinize the different stations which these 
plants occupy, we might say, in observing E 
