GEOGRAPHICAL DISTRIBUTION OF PLANTS. 553 
find other plants, very different from the masses he looked at in 
the distance, which we call Alpine plants—such as the Aconites, 
Astrantia, certain species of Artemisias, of Groundsel, Prenanthes, 
Achilleas, Saxifrages, and Potentillas. After having skirted the 
Walnut-trees, and traversed the woods formed of Chesnut-trees, 
these will be observed to cease, and forests of Oaks, Beeches, and 
Birches take their place. Of these, the Oaks disappear first, at the 
height of about two thousand five hundred feet above the level of 
the sea, the Beeches about three thousand. Beyond this the trees 
consist entirely of evergreen trees, as Firs, Larches, and the common 
Pine, which stop also at certain successive stages, about four thou- 
sand five hundred feet. The Birch ascends a little higher, but dis- 
appears also at about six thousand feet of elevation. A conifer 
(Pinus cembro) continues for another hundred yards. Beyond this 
limit the trees become dwarfed in size; for example, a species of 
Alder (Alnus viridis) becomes a low shrub. Near to this the botanist 
will find himself surrounded by shrubs very characteristic of the 
Alps, sometimes called the Alpine Rose, namely, the Rhododendron, 
which ceases in its turn only a little higher, giving place to plants © 
much more lowly, which scarcely rise above the soil. These are 
specially known as Alpine plants. They belong to families which he 
observed at his point of departure. A few Crucifers, Caryophyl- 
lum, Rosacexw, Liguminosex, Composite, Cypriacexe, Graminex, but 
of different species. These also are numerous, and with them 
representatives of other families which rarely show themselves in 
the plains, such as Saxifrages, Gentians. Annuals cease almost 
entirely, as might be foreseen, since an unfavourable season, in 
which the ripening of their seeds was checked, would be sufficient 
< to destroy their race.’ : 
The roots of perennial or woody plants bury themselves under 
the soil, where a higher temperature is preserved. They submit 
themselves to the influence of the atmosphere and develop them- 
selves when it is milder and sufficiently warm. But this can only 
be done during a short season, and on some places only once 
in many years. It follows that the stems are short and scarcely 
rise out of the soil, while those that are frutescent usually hug 
the ground, sometimes creeping, sometimes raising short, hardy, 
intertwining stems, forming thick stunted bushes, as would result 
