We In Vain Hoped To Find On The Mountains Of Caracas, And Subsequently On The Back Of The Andes, An Eglantine Near These Brambles.

We did not find one indigenous rose-tree in all South America, notwithstanding the analogy existing between the climates of the high mountains of the torrid zone and the climate of our temperate zone.

It appears that this charming shrub is wanting in all the southern hemisphere, within and beyond the tropics. It was only on the Mexican mountains that we were fortunate enough to discover, in the nineteenth degree of latitude, American eglantines.* (* M. Redoute, in his superb work on rose-trees, has given our Mexican eglantine, under the name of Rosier de Montezuma, Montezuma rose.)

We were sometimes so enveloped in mist, that we could not, without difficulty, find our way. At this height there is no path, and we were obliged to climb with our hands, when our feet failed us, on the steep and slippery acclivity. A vein filled with porcelain-clay attracted our attention.* (* The breadth of the vein is three feet. This porcelain-clay, when moistened, readily absorbs oxygen from the atmosphere. I found, at Caracas, the residual nitrogen very slightly mingled with carbonic acid, though the experiment was made in phials with ground-glass stoppers, not filled with water.) It is of snowy whiteness, and is no doubt the remains of a decomposed feldspar. I forwarded a considerable portion of it to the intendant of the province. In a country where fuel is not scarce, a mixture of refractory earths may be useful, to improve the earthenware, and even the bricks. Every time that the clouds surrounded us, the thermometer sunk as low as 12 degrees (to 9.6 degrees R.); with a serene sky it rose to 21 degrees. These observations were made in the shade. But it is difficult, on such rapid declivities, covered with a dry, shining, yellow turf, to avoid the effects of radiant heat. We were at nine hundred and forty toises of elevation; and yet at the same height, towards the east, we perceived in a ravine, not merely a few solitary palm-trees, but a whole grove. It was the palma real; probably a species of the genus Oreodoxa. This group of palms, at so considerable an elevation, formed a striking contrast with the willows* scattered on the depth of the more temperate valley of Caracas. (* Salix Humboldtiana of Willdenouw. On the alpine palm-trees, see my Prolegomena de Dist. Plant. page 235.) We here discovered plants of European forms, situated below those of the torrid zone.

After proceeding for the space of four hours across the savannahs, we entered into a little wood composed of shrubs and small trees, called el Pejual; doubtless from the great abundance here of the pejoa (Gaultheria odorata), a plant with very odoriferous leaves.* (* It is a great advantage of the Spanish language, and a peculiarity which it shares in common with the Latin, that, from the name of a tree, may be derived a word designating an association or group of trees of the same species. Thus are formed the words olivar, robledar, and pinal, from olivo, roble, and pino. The Hispano-Americans have added tunal, pejual, guayaval, etc., places where a great many Cactuses, Gualtheria odoratas, and Psidiums, grow together.) The steepness of the mountain became less considerable, and we felt an indescribable pleasure in examining the plants of this region. Nowhere, perhaps, can be found collected together, in so small a space, productions so beautiful, and so remarkable in regard to the geography of plants. At the height of a thousand toises, the lofty savannahs of the hills terminate in a zone of shrubs which, by their appearance, their tortuous branches, their stiff leaves, and the magnitude and beauty of their purple flowers, remind us of what is called, in the Cordilleras of the Andes, the vegetation of the paramos and the punas.* (* For the explanation of these words, see above Chapter 1.5.) We there find the family of the alpine rhododendrons, the thibaudias, the andromedas, the vacciniums, and those befarias with resinous leaves, which we have several times compared to the rhododendron of our European Alps.

Even when nature does not produce the same species in analogous climates, either in the plains of isothermal parallels,* (We may compare together either latitudes which in the same hemisphere present the same mean temperature (as, for instance, Pennsylvania and the central part of France, Chile and the southern part of New Holland); or we may consider the relations that may exist between the vegetation of the two hemispheres under isothermal parallels.) or on table-lands, the temperature of which resembles that of places nearer the poles,* we still remark a striking resemblance of appearance and physiognomy in the vegetation of the most distant countries. (* The geography of plants comprises not merely an examination of the analogies observed in the same hemisphere; as between the vegetation of the Pyrenees and that of the Scandinavian plains; or between that of the Cordilleras of Peru and of the coasts of Chile. It also investigates the relations between the alpine plants of both hemispheres. It compares the vegetation of the Alleghanies and the Cordilleras of Mexico, with that of the mountains of Chile and Brazil. Bearing in mind that every isothermal line has an alpine branch (as, for instance, that which connects Upsala with a point in the Swiss Alps), the great problem of the analogy of vegetable forms may be defined as follows: 1st, examining in each hemisphere, and at the level of the coasts, the vegetation on the same isothermal line, especially near convex or concave summits; 2nd, comparing, with respect to the form of plants, on the same isothermal line north and south of the equator, the alpine branch with that traced in the plains; 3rd, comparing the vegetation on homonymous isothermal lines in the two hemispheres, either in the low regions, or in the alpine regions.) This phenomenon is one of the most curious in the history of organic forms.

Enter page number Go  Previous Next
Page 175 of 208
Words from 177541 to 178556 of 211363