ON THE VEGETATION OF ETNA. 93 
mer months, no snow remains lying on the 
summit of Etna, and a frightful desert of 
black fields of lava and ashes commences, 
where there is no trace of life, and nothing 
can be seen but the tracks of mules and the 
bones of these animals, which often excite 
the curiosity and the enquiries of persons 
who visit these gloomy and barren heights. 
Of the region of Lichens, to which Presl 
assigns an extent of 200 feet above the ele- 
vation of 9,000, I could see nothing, and in 
general the higher parts of Etna are very poor 
in Cryptogamia. Bryum sanguineum (?) 
grows at 7,900 feet, Grimmia leucophaa 
at 7,110, and Geastrum hygrometricum 
(Pers.), with Nidularia Crucibulum (Pt), 
at 3,000 feet. 
After having thus defined the propor- 
tions of vegetation upon Etna, I shall pro- 
ceed to make some observations, by way 
of comparing this mountain with others, 
especially with the Alps, which are situated 
about eight degrees and a half to the north- 
ward, and with the Canary Islands, lying 
nine degrees and a half southward, thus 
placed at about equal distances from it. 
What strikes most forcibly at first is the 
great poverty of species and of individual 
plants that prevails in the woody and upper 
regions of Etna, as compared with the im- 
mense contrast presented by the varied 
forms and luxuriant vegetation that clothe 
the Alps. Still Etna is rich, when viewed 
in comparison with the scanty produce of 
the Canary Islands. To the upper region 
of the Peak of Teneriffe, an elevation of 
above 5,900 feet, Von Buch assigns only 
twenty-three species of plants, while, at a 
t of 6,200 feet, Etna produces about 
fifty-two species. The reasons for this dis- 
mer is not the case with Etna; but its 
drought May serve to explain the poverty 
of its vegetation, The top of the mountain 
18 rarely covered with clouds, (though this 
may be the case with the Peak); no springs 
burst from its volcanic sides, the little water 
png down from Etna only comes be- 
low where the lava covers the original 
clayey soil, as at Aci, Paterno, Aderno, 
&c., and there is no perpetual snow lying 
on the summit, whose gradual melting in 
summer would constantly keep the ground 
in a state of moisture. Rain rarely falls, 
which is attributable both to Etna being in 
a southern latitude and to its insolated situ- 
ation, which forbids its retaining the clouds 
in their passage, as is the case with entire 
ranges of mountains. The number of rainy 
days in Catania is stated, by M. Gemmel- 
laro, as only sixty-three; and in Palermo, 
where the average is sixty-four, the quan- 
tity of rain that annually falls is said to be 
twenty-two English inches; while, on the 
southern side of the Alps, the mean quan- 
tity is stated at fifty-four, and on the plains 
of Lombardy thirty-six. Another important 
reason is the peculiar nature of the soil; 
for the long series of a thousand years, the 
original surface of the Alps has been con- 
tinually exposed to every influence of the 
weather, and no event of nature has dis- 
turbed the gradual formation of fruitful soil 
and the increase of vegetation upon it: 
but it is far different with Etna, especially 
on the higher regions. A fresh flow of 
lava, a new field of ashes, thickly and 
speedily cover the scanty vegetation, while 
another eruption destroys in a moment the 
slow and gradual production of centuries. 
Suffice it to say, that fifty-four eruptions 
have been known to take place, the average 
being one in every thirty-three years, thus 
allowing only a similar period as the age 
of the soil on the highest regions of this 
mountain. 
The following is a tolerably correct list 
of the plants which grow above the boun- 
dary line of trees upon Etna :— 
Juniperus hemispherica, Presl, Berberis 
Etnensis, Presl, (a variety only of B. vul- 
garis), Astragalus Siculus, Bivona, and 
Cardamine thalictroides, the latter is 
stated by Pres] to be peculiar to Etna, as 
well as Arenaria aristata, which is, how- 
ever, a doubtful species; A. serpylhfolia, 
Saponaria Etnensis, Potentilla argentea, 
Helianthemum glaucum, and H. levipes, 
which latter grows also on the sea shore, - 
Viola gracilis, Sibth., Cerastium tomento- 
