It seems to resemble P. Cembra in its way of growth, and is confined to mountains of Triassic and limestone formation, where it forms a zone of scattered forest just below the limit of trees, usually not more than 1000 feet in depth, and finds its lowest level at 1000 metres on the Preslica planina, according to Reiser, near the railway station of Bradina; ascending on the Prenj and Orjen mountains to 1700 or 1800 metres. At the lowest elevation it is mixed with beech; at the highest with P. montana, Juniperus nana, and J. sabina.
In some places at the upper levels, where the snow lies very deep, it becomes very stunted, not rising more than 2 to 4 metres from the ground, but does not assume the procumbent habit of P. montana. It roots itself so firmly on the dry bare rocks of these mountains that no wind can hurt it, and it endures the burning sun and bitter winds of this region without injury. I am indebted to Herr Reiser of Serajevo for the photographs showing the habit of this tree (Plate 119).
In the upper Idbar valley there is a forest where P. leucodermis grows mixed with spruce, silver fir, Austrian pine, and yew, as well as with beech, ash, sycamore, Pyrus torminalis, and Acer obtusatum. ts smooth grey bark,’ divided into irregular segments, makes it very easy to distinguish from the Austrian pine, but Beck does not think the name of whitebark pine so applicable as that of Panzerföhre or armoured pine. The tree attains under favourable circumstances a height of 90 feet, with a diameter of 6 feet at the age of 294 years.
Of its timber Beck says nothing, but a story which was current in Bosnia when I was there in 1899, and which doubtless has some foundation, leads one to suppose that it is very hard. A Bosnian Turk was said to have bought a lot of trees of this species, which he felled and floated down the Narenta, and sold the timber as that of larch.
With regard to the occurrence of this species elsewhere, Christ described as a new species, Pinus Heldreichii,’ specimens which were collected on Mount Olympus in Thessaly. Afterwards, in a letter to Dr. Masters, he stated that this is only a remarkable alpine variety of Pinus Laricio, very reduced, and approaching in some respects Pinus montana. Halacsy* considers that this tree, which grows on Mount Olympus in company with the ordinary form of Laricio and with Abies Apollonis, is identical with Pinus leucodermis.
A tree referred to this species has been recently found in southern Italy by Dr. Biagio Longo. He mentions‘ two localities, the alpine zone of the Calabrian Apennines from Orsomarso to Mount Montea, and the mountain of La Spina in the province of Basilicata, where it grows in the zone of the beech, and rivals that tree in thickness of trunk; but the foresters in the Sila mountains do not recognise this as a distinct species, or did not know of its discovery when I was there in 1903.
Seeds were sent by Beck to Kew in October 1890; and five plants were raised, which have grown with remarkable slowness, being only 9 to 12 inches high in 1901.
1 The bark is figured in Hempel u. Wilhelm, Baüme u. Sträucher, i. 161, fig. 84 (1889).
2 Christ, in Verh. Naturf. Ges. Basel, iii. 549 (1863), but later, in Flora, l. 83 (1867), he states that Pinus Heldreichii is identical with P. leucodermis, which he considers to be only an alpine variety of P. Laricio.
3 Consp. Fl. Græcæ, iii. 453 (1904).
4 Annali di Botanica, iii. 13, 17 (1905), iv. 55 (1906).
