Of the 114 species of the Genus Pinus with which we are at present acquainted, not one belongs to the Southern Hemisphere, for the Pinus merkusii described by Junghuhn and De Vriese belongs to the part of the Island of Sumatra which is north of the Equator, to the district of the Battas; and Pinus insularis (Endl.) although it was at first given in Loudon’s Arboretum as P. timoriensis, really belongs to the Philippines. Besides the Genus Pinus, the Southern hemisphere, according to the present state of our now happily advancing knowledge of the geography of plants, is entirely without species of Cupressus, Salisburia (Gingko), Cunninghamia (Pinus lanceolota, Lamb.) Thuja, (one of the species of which, Th. gigantea, Nutt., found on the banks of the Columbia, has a height of above 180 Eng. feet), Juniperus, and Taxodium (Mirbel’s Schubertia). I include the last-named genus with the less hesitation, as a Cape of Good Hope plant (Sprengel’s Schubertia capensis) is no Taxodium, but constitutes a genus of itself, Widringtonia, (Endl.) in quite a different division of the family of Coniferæ.
This absence, from the Southern Hemisphere, of true Abietineæ, Juniperineæ, Cupressineæ, and all the Taxodineæ, as well as of Torreya, Salisburia adiantifolia, and Cephalotaxus from among the Taxineæ, recalls forcibly the obscurity which still prevails in the conditions which have determined the original distribution of vegetable forms, a distribution which cannot be sufficiently and satisfactorily explained solely by similarity or diversity of soil, thermic relations, or meteorological phenomena. I remarked long ago that the Southern Hemisphere for example has many plants belonging to the natural family of Rosaceæ, but not a single species of the genus Rosa. We learn from Claude Gay that the Rosa chilensis described by Meyen is only a wild variety of the Rosa centifolia (Linn.), which has been for thousands of years a European plant. Such wild varieties, (i. e. varieties which have become wild) occupy large tracts of ground in Chili, near Valdivia and Osorno. (Gay, Flora Chilensis, p. 340.)
In the tropical region of the Northern hemisphere we also found only one single native rose, our Rosa montezumæ, in the Mexican highlands near Moran, at an elevation of 8760 (9336 Engl.) feet. It is one of the singular phenomena in the distribution of plants, that Chili, which has Palms, Pourretias, and many species of Cactus, has no Agave; although A. americana grows luxuriantly in Roussillon, near Nice, near Botzen and in Istria, having probably been introduced from the New Continent since the end of the 16th century, and in America itself forms a continuous tract of vegetation from Northern Mexico across the isthmus of Panama to the Southern part of Peru. I have long believed that Calceolarias were limited like Roses exclusively to one side of the Equator; of the 22 species which we brought back with us, not one was collected to the north of Quito and the Volcano of Pichincha; but my friend Professor Kunth remarks that Calceolaria perfoliata, which Boussingault and Captain Hall found at Quito, advances to New Granada, and that this species, as well as C. integrifolia of Santa Fé de Bogotá, were given by Mutis to the great Linnæus.
The species of Pinus which are so frequent in the tropical Antilles and in the tropical mountains of Mexico do not pass the isthmus of Panama, and are not found in the equally mountainous parts of the tropical portion of South America, and in the high plains of New Granada, Pasto, and Quito. I have been both in the plains and on the mountains from the Rio Sinu, near the isthmus of Panama, to 12° S. lat.; and in this tract of almost 1600 geographical miles the only forms of needle-trees which I saw were a Taxus-like species of Podocarpus with stems 60 (64 Eng.) feet high (Podocarpus taxifolia), growing in the 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 Coniferæ there are common to the northern and southern hemispheres the genera Taxus, Gnetum, Ephedra, and Podocarpus. The last-named genus was distinguished from Pinus long before L’Heritier by Columbus himself, who wrote on the 25th of November, 1492: “Pinales en la Serrania de Haiti que no llevan piñas, pero frutos que parecen azeytunos del Axarafe de Sevilla.” (See my Examen crit. T. iii. p. 24.) There are species of Taxus from the Cape of Good Hope to 61° N. lat. in Scandinavia, or through more than 95 degrees of latitude; Podocarpus and Ephedra extend almost as far. In Cupuliferæ, the species of oak which we are accustomed to regard as a northern form do not indeed pass beyond the equator in South America, but in the Indian Archipelago they re-appear in the southern hemisphere in the Island of Java. To the southern hemisphere belong exclusively ten genera of Coniferæ, of which I will name here only the principal: Araucaria, Dammara (Agathis Sal.), Frenela (with eighteen New Holland species), Dacrydium and Lybocedrus, which is found both in New Zealand and at the Straits of Magellan. New Zealand has one species of the genus Dammara (D. australis) and no Araucaria. In New Holland in singular contrast the case is opposite.
Among tree vegetation, it is in the form of needle-trees that Nature presents to us the greatest extension in length (longitudinal axis): I say among tree vegetation, because, as we have already remarked, among oceanic Algæ, Macrocystis pyrifera, which is found between the coast of California and 68° S. lat., often attains from 370 to 400 (about 400 to 430 Eng.) feet in length. Of Coniferæ, (setting aside the six Araucarias of Brazil, Chili, New Holland, Norfolk Island, and New Caledonia), the loftiest are those which belong to the northern temperate zone. As in the family of Palms we found the most gigantic, the Ceroxylon andicola, above 180 French (192 English) feet high, in the temperate mountain climate of the Andes, so the loftiest Coniferæ belong, in the northern hemisphere, to the temperate north-west coast of America and to the Rocky Mountains (lat. 40°-52°); and in the southern hemisphere to New Zealand, Tasmania or Van Diemen Island, the south of Chili and Patagonia (between 43° and 50° latitude). The most gigantic forms belong to the genera of Pinus, Sequoia (Endl.), Araucaria, and Dacrydium. I propose to name only those species which not only attain but often exceed 200 French feet (213 Eng.) In order to afford a standard of comparison, it should be remarked that in Europe the tallest Red and White Pines, the latter especially, attain about 150 or 160 (160-170 Eng.) feet; that, for example, in Silesia the Pine of the Lampersdorf Forest near Frankenstein enjoys great celebrity, although, with a circumference of 17 English feet, its height is only 153 Prussian, or 148 French, or 158 English feet. (Compare Ratzeburg, Forstreisen, 1844, S. 287.)
Pinus grandis (Douglas) in New California attains 224 English feet.
Pinus frémontiana (Endl.), also in New California, probably attains the same stature as the preceding. (Torrey and Frémont, Report of the Exploring Expedition to the Rocky Mountains in 1844, p. 319.)
Dacrydium cupressinum (Solander), from New Zealand, 213 English feet.