Page:Transactions NZ Institute Volume 17.djvu/386

304 plates often projecting from one to two inches beyond the sound portion of the trunk, and exhibiting thin, rounded, weather-worn edges, but perfectly sound, and extremely hard. They vary from $1⁄16$ to $1⁄8$ inch in thickness at the base, and may be easily broken off by a sharp blow with a hammer. Unripe trees do not exhibit this peculiarity.

The remarkable difference in the pubescence of the leaf at different stages of growth has not received the attention it deserves. In the young state the leaves are nearly membranous, and perfectly glabrous. In exposed mature specimens the under surface of the leaves is clothed with a layer of closely appressed hairs; but it is quite a common occurrence to find trees thirty feet high or more with leaves destitute of this hairy covering when growing under the shelter of taller trees. These hairs are unquestionably adapted to prevent undue evaporation and injury from sudden variations in temperature. Accordingly we only find them developed on leaves fully exposed to the sun and air, whether on young trees or old. They are never developed on seedling plants, or on branches growing under the shade of taller trees. The series of specimens now exhibited will be found very instructive on this head.

This species appears to attain its northern limit at the East Cape, where it forms a small tree 20 to 30 feet in height. It is plentiful on the lower slopes of the Ruahine, Tararua, and Rimutaka Mountains, in the North Island, and widely distributed in the South Island, but does not appear to extend to Foveaux Straits. It descends to the sea-level at Lowry Bay and other places, but appears to be replaced by the mountain beech, which is often mistaken for it. At altitudes above 2,800 feet, with some few exceptions.

Specimens 100 feet high were observed by Mr. Bidwill at Waiwetu, near Wellington.

The mountain beech bears a close resemblance to the entire-leaved beech in general appearance, although it never attains the extreme dimensions of that species. The leaves are pointed at the apex and rounded or cordate at the base, so that there is but little difficulty in distinguishing the two kinds.

In the North Island it is confined to the mountain ranges, and appears to attain its northern limit at Lake Waikare on the East Cape. It is most