Far above the regions of Alpine herbs, of the grasses and the lichens, nay, beyond the boundary of perpetual snow, there occasionally appears a phanerogamic plant, growing sporadically, and as it were isolated, to the astonishment of botanists; and this occurs both within the tropics and in the temperate zone, on fragments of rock which remain free from snow and are probably warmed by open fissures. I have already mentioned the Saxifraga Boussingaulti, which is found at a height of 15,773 feet on the Chimborazo; in the Swiss Alps the Silene acaulis, a clovewort or caryophyllea, has been seen at a height of 11,382 feet. The former vegetates at 640, the latter at 2621 feet above the respective local limits of snow, heights which were determined when both the plants were discovered.
In our European Coniferous woods the Red Pine (or Norway Spruce), and the White (or Silver) Pine show great and remarkable variations as regards their geographical dispersion on the slopes of mountains. Whilst in the Swiss Alps the Red Pine (Pinus picea, Du Roi, foliis compressotetragonis; unfortunately named by Linnæus and by most botanists of our time the Pinus abies!), forms the limit of tree vegetation at the mean height of 5883 feet, and only here and there does the lowly alder (Alnus viridis, Dec., Betula viridis, Vill.), advance higher towards the snow-limit; the White Pine (Pinus abies, Du Roi, Pinus picea, Linn., foliis planis, pectinato-distichis, emarginatis), has its limit, according to Wahlenberg, about 1000 feet lower. The Red Pine does not grow at all in Southern Europe, in Spain, the Apennines, and Greece; and, as Ramond remarks, it is only seen on the slope of the northern Pyrenees at great heights, and is entirely wanting in the Caucasus. The Red Pine extends further to the north in Scandinavia than the White, which latter tree appears in Greece (on the Parnassus, the Taygetus, and the Œta), as a variety with long acicular leaves, foliis apice integris, breviter mucronatis, the Abies Apollinis of the acute observer Link.[[PD]]
On the Himalaya the acicular-leaved form of trees is distinguished by the mighty thickness and height of the stem as well as by the length of the leaf. The chief ornament of the mountain range is the Cedar Deodwara (Pinus deodara, Roxb.), which word is, in Sanscrit, dêwa-dâru, i.e. timber for the gods, its stem being nearly from 13 to 14 feet in diameter. It ascends in Nepaul to more than 11,700 feet above the level of the sea. More than 2000 years ago the Deodwara cedar near the River Behut, that is, the Hydaspes, furnished the timber for the fleet of Nearchus. In the valley of Dudegaon, north of the copper mines of Dhunpoor in Nepaul, Dr. Hoffmeister, so early lost to science, found in a forest the Pinus longifolia (Royle), or the Tschelu Fir, mixed with the lofty stems of a palm—Chamærops martiana (Wallich).[[PE]] Such an interspersion of the pineta and palmeta had already, in the new continent, excited the astonishment of the companions of Columbus, as a friend and contemporary of the admiral’s, Petrus Martyr Anghiera, relates.[[PF]] I myself saw, for the first time, this blending of pines with palms on the road from Acapulco to Chilpanzingo. The Himalaya, like the Mexican highlands, besides its genera of pine and cedar, possesses also forms of the Cypress (Cupressus torulosa, Don.); of the Yew (Taxus Wallichiana, Zuccar.); of the Podocarpus (Podocarpus nereifolia, Brown); and the Juniper (Juniperus squamata, Don., and J. excelsa, Bieberst.; the latter species occurring also at Schipke in Thibet, in Asia Minor, Syria, and the Grecian Islands; on the other hand, Thuja, Taxodium, Larix, and Araucaria, are forms of the New Continent, which are wanting in the Himalaya.
Besides the twenty species of pine with which we are acquainted in Mexico, the United States of North America, in their present extension to the Pacific, present forty-five described species, whilst all Europe can only enumerate fifteen. The same difference between abundance and paucity of forms is shown in the oaks, in favour of the New Continent (a quarter of the world the most connected and most elongated in a meridional direction). It has, however, been very recently demonstrated by the extremely accurate researches of Siebold and Zuccarini to be an erroneous assertion, that many European species of pine, in consequence of their wide distribution throughout Northern Asia, passed over to the Japanese islands, and there mingled with a genuine Mexican species, the Weymouth pine (Pinus strobus, L.), as Thunberg asserts. What Thunberg considered to be European species of pine, are species entirely different. Thunberg’s Red Pine (Pinus abies, Linn.) is P. polita, Sieb., and often planted near Buddhist temples; his northern common fir (Pinus sylvestris) is P. Massoniana, Lamb.; his P. cembra, the German and Siberian stone pine-tree, is P. parviflora, Sieb.; his common larch (P. larix) is the P. leptolepis, Sieb.; his Taxus baccata, the fruit of which the Japanese courtiers eat as a precautionary measure when attending long ceremonies,[[PG]] forms a special genus and is Cephalotaxus drupacea, Sieb. The Japanese islands, despite the proximity of the Asiatic Continent, have a very different character of vegetation. Thunberg’s Japanese Weymouth pine, which would present an important phenomenon, is moreover a naturalized tree, that differs entirely from the indigenous pines of the New World. It is Pinus korajensis, Sieb., which has migrated from the peninsula of Corea and Kamtschatka to Nipon.
Of the 114 species now known of the genus Pinus, there is not one in the whole southern hemisphere, for the Pinus Merkusii, described by Junghuhn and De Vriese, still belongs to that part of the island of Sumatra which is north of the equator, that is, to the district of the Battas. The P. insularis, Endl., belongs to the Philippines, although at first it was introduced into Loudon’s Arboretum as P. timoriensis. From our present increasing knowledge of the geography of plants, we know that there are excluded also from the southern hemisphere, in addition to the genus Pinus, all the races of Cupressus, Salisburia (Ginkgo), Cunninghamia (Pinus lanceolata, Lamb.), Thuja, one species of which (Th. gigantea, Nutt.) at the Columbia river rises as high as 180 feet, Juniperus, and Taxodium (Mirbel’s Schubertia). I can introduce this last genus here with the greater certainty, inasmuch as a Cape plant, Sprengel’s Schubertia capensis, is no Taxodium, but forms a special genus, Widringtonia, Endl., in quite another division of the Coniferæ.
This absence from the southern hemisphere of the true Abietineæ, of the Juniperineæ, Cupressineæ, and all the Taxodineæ, as likewise of the Torreya, of the Salisburia adiantifolia, and of the Cephalotaxus among the Taxineæ, vividly reminds us of the enigmatical and still obscure conditions which determined the original distribution of vegetable forms. This distribution can by no means be satisfactorily explained either by the similarity or diversity of the soil, by thermal relations, or by meteorological conditions. I have long since directed attention to the fact, that the southern hemisphere possesses, for instance, many plants of the natural family of the Rosaceæ, but not a single species of the genus Rosa itself. Claude Gay informs us, that the Rosa Chilensis, described by Meyen, is a variety that has become wild of the Rosa centifolia, Linn., which has been naturalized in Europe for thousands of years. Such wild-growing varieties occupy large tracts in Chili near Valdivia and Osorno.[[PH]]
In the whole tropical region of the northern hemisphere we only found one single indigenous rose, our Rosa Montezumæ, and this was on the Mexican highland, near Moran, at a height of 9336 feet. We may count among the strange phenomena observed in the distribution of plants, the total absence of the Agave from Chili, though it possesses Palms, Pourretias, and many species of Cactus; and although A. americana flourishes luxuriantly in Roussillon, at Nice, at Botzen, and in Istria, where it was probably introduced from the New Continent since the sixteenth century, and where it forms one connected line of vegetation from the north of Mexico, across the isthmus of Panama, as far as Southern Peru. With respect to the Calceolarias, I long believed that, like the roses, they were only to be found exclusively on the northern side of the equator. In fact, among the twenty-two species that we brought with us, not one was gathered to the north of Quito and the volcano of Pichincha; but my friend Professor Kunth remarks that Calceolaria perfoliata, which Boussingault and Capt. Hall found near Quito, advances also as far as New Granada, and that this species, as well as C. integrifolia, was sent by Mutis from Santa Fé de Bogotá to the great Linnæus.
The species of Pinus, which are so abundant in the wholly inter-tropical Antilles, as well as in the tropical mountain regions of Mexico, do not cross the isthmus of Panama, and are wholly wanting in the equally mountainous parts of tropical South America, that lie north of the equator; they are equally unknown on the elevated plains of New Granada, Pasto, and Quito. I have advanced in the plains and on the mountains from the Rio Sinu, near the isthmus of Panama, as far as 12° south lat.; and in this territorial extent, of nearly 1600 miles in length, the only forms of needle-leaved trees that I saw, were the taxoid Podocarpus (P. taxifolia), 64 feet high, in the Andes pass of Quindiu and in the Paramo de Saraguru, in 4° 26′ north and 3° 40′ south latitude, and an Ephedra (E. americana) near Guallabamba, north of Quito.
Among the group of the Coniferæ, the following are common to the northern and southern hemispheres: Taxus, Gnetum, Ephedra, and Podocarpus. Long before l’Heritier, the last genus had been very properly distinguished from Pinus by Columbus on the 25th of November, 1492. He says, “Pinales en la Serrania de Haiti que no llevan piñas, pero frutos que parecen azeytunos del Axarafe de Sevilla.”[[PI]] Species of yew extend from the Cape of Good Hope to 61° north lat. in Scandinavia, consequently through more than 95 degrees of latitude. Podocarpus and Ephedra are almost as widely distributed; and even from among the Cupuliferæ, the species of the oak genus, usually termed by us a northern form, though they do not cross the equator in South America, reappear in the southern hemisphere, at Java, in the Indian archipelago. To this latter hemisphere ten genera of the cone-bearing trees exclusively appertain, of which we will here cite only the most important: Araucaria, Dammara (Agathis, Sal.), Frenela (comprising about 18 Australian species), Dacrydium and Lybocedrus, whose habitat is both in New Zealand and the Straits of Magellan. New Zealand possesses one species of the genus Dammara (D. australis), but no Araucaria. The contrary, by a singular contrast, is the case in New Holland.
In the form of acicular-leaved trees, Nature presents us with the greatest length of stem existing in arborescent productions. I use the term arborescent, for, as we have already remarked, among the Laminariæ (the oceanic algæ) Macrocystis pyrifera, between the coast of California and 68° south lat., often attains a length of more than 400 feet. If we exclude the six Araucarias of Brazil, Chili, New Holland, the Norfolk Islands and New Caledonia, then those Coniferæ are the highest, whose habitat is the temperate zone of the North. As we have found among the family of the palms the most gigantic of all, the Ceroxylon andicola, about 192 feet high, in the temperate Alpine climate of the Andes, so in like manner do the loftiest cone-bearing trees belong, in the northern hemisphere, to the temperate north-western coast of America and to the Rocky Mountains (lat. from 40° to 52°), in the southern hemisphere to New Zealand, Tasmania or Van Dieman’s Land, to Southern Chili and Patagonia, (where the lat. is again from 43° to 50°). The most gigantic forms among the genus Pinus are Sequoia (Endl.), Araucaria, and Dacrydium. I only name those species whose height not merely reaches but often exceeds 200 feet. That the reader may have a standard of comparison, he is reminded that in Europe the loftiest Red and White Pines, especially the latter, reach a height of from 160 to 170 feet; for instance, in Silesia, the pine in the Lampersdorf forest, near Frankenstein, long famous for its altitude, is only 158 feet high, although 17 feet in girth.[[PJ]]