138. The timber trees of the native forests of Italy are chiefly oak, chestnut, and beech; the undergrowths are of numerous species, including the A'rbutus, Quercus, I'lex, and myrtle. This class of forests skirts the Alpine mountains, and covers, in many places, the Apennine hills. In higher regions the larch abounds, and in sheltered dells the silver fir. The stone and cluster pine are confined to the lower regions, as the hills of Tuscany, the vales of Arno, Tiber, &c.