At length we started on the road by the left bank which I had followed on the previous evening, and, the weather being again nearly perfect, I thoroughly enjoyed a very charming excursion, which carried me farther into the heart of the Cordillera than I had yet reached. As very often happens, however, the nearer one gets to the great peaks the less one is able to see of them. The general outline of the slopes in the inner valleys of high mountain countries is usually convex, because the torrents have deepened the trench between opposite slopes more quickly than subaërial action has worn away the flanks; and it is only exceptionally that the summits of the ridges can be seen from the intervening valley. Among mountains where the main lines of valley are, so to say, structural—i.e. depending on inequalities produced during the original elevation of the mountain mass—the case is somewhat different. Such valleys are usually nearly straight, as we see so commonly in the European Alps, and the peaks lying about the head of the valley are therefore often in view; but in the Andes, as in many parts of the Rocky Mountains, it would appear that the valleys are exclusively due to erosive action, and, their direction being determined by merely local conditions, they are extremely sinuous, and rarely follow the same direction for any considerable distance.
The road up the Aconcagua valley seemed to me at the time to be about the worst over which I ever travelled in a carriage, but I had not then made acquaintance with the mountain tracks, which they are pleased to call roads, in the United States. Looking back in the light of subsequent experience, I suppose that the Chilian roads should rank among the best in the American continent, although this one was so uneven that in awkward places, where it overhung the river, the carriage was often tilted so much to one side that I was thankful not to have with me a nervous companion.
About half-way to the Resguardo the road crosses the river by a stone bridge, where it rushes in a narrow channel between high rocky banks. Seeing botanical inducements, I descended to examine the banks on either side, and in crossing the bridge noticed, what I might otherwise have overlooked, that the crown of the arch was rapidly giving way. There was a large hole in the centre, and the structure was sustained only by the still solid masonry on each side, where the wear and tear had been less constant. I have often admired the calm good sense displayed by the horses in all parts of America, and was interested in observing the prudent way in which our steeds selected the safest spots on either side of the hole without any appearance of the nervousness which seems hereditary in English horses, partly due, I suppose, to the unnatural conditions in which they live. With every confidence in animal sagacity, but none whatever in the stability of the bridge, I thought it judicious on my return in the evening to recross it on foot.
A SENSITIVE PLANT.
I found two or three curious plants not before seen on the rocks here, and again found the singular Zygophyllaceous shrub Porliera hygrometrica, which is not uncommon in this part of Chili. The numerous stiff spiny branches diverging at right angles must produce flowers during a great part of the year, as I observed at this season both nearly ripe fruit and flowers in various stages of development. The small pinnate leaves, somewhat resembling in form those of the sensitive plant, have something of the same quality. But in this case the effective stimulus seems to be that of light, causing them to expand in sunshine and to close when the sky is covered. If at all, they must be very slightly affected by contact, as I failed to observe it. If I am correct, the appropriate specific name would be photometrica rather than hygrometrica.
In the hedges and among the bushes a pretty climbing plant (Eccremocarpus scaber) seemed to be common on the right bank of the stream, producing flower and ripe fruit at the same time. It belongs to the trumpet-flower tribe (Bignoniaceæ), though not rivalling in size or brilliancy of colour the true Bignonias which I afterwards saw in Brazil.
Having passed on the left the opening of a narrow valley which appears to contain the main stream of the Aconcagua, I reached the Resguardo somewhat before noon, and proceeded at once to deliver my letter to Captain X——, the officer commanding the frontier station. I was most courteously received, with a pressing invitation to join the almuerzo, or luncheon, which is the ordinary midday meal in Chili. Besides the lady of the house, I met at table an officer of the Chilian navy, a friend of my host, who had come to recruit in mountain air after recovery from a serious illness, and who spoke English fairly well. The conversation was interesting, and I was struck by the excellent tone and quick intelligence displayed by these agreeable specimens of Chilian society. In the kindest way, and with evident sincerity, my host pressed me to remain for a week at his house, and promised me many excursions in the neighbourhood. It was with real reluctance that, owing to imperious engagements, I was forced to decline the hospitable invitation; and it has been a further regret that, having failed to note it at the time, my treacherous memory has not retained the name of this amiable gentleman.
Meanwhile, although the time passed so pleasantly, I was burning with the desire to make use of the brief interval available for seeing something of the surrounding country. The Resguardo stands at the junction of a rivulet that descends from the Uspallata Pass with the Rio Colorado, which flows from the north-east apparently from the roots of the great peak of Aconcagua. As far as I could see, the track leading to the pass wind in zigzags up steep slopes, at this season almost completely bare of vegetation, and I decided on following the valley of the Rio Colorado, where, at least along the banks of the stream, vegetation was comparatively abundant. My obliging host had provided a horse and a guide, and I rode for about an hour up the valley, which in great part is narrowed nearly to a ravine. In one place, where it widens to a few hundred yards, I passed a peasant’s cottage, with a few stony fields from which the crop had been gathered.
THE VERBENA FAMILY.
Among the plants not before observed, I was at first puzzled by a sort of thicket of long green leafless stems eight or ten feet in height, growing near the stream. Only after searching for some time I detected some withered remains of a short spike of flowers at the ends of the stems, which showed the plant to be of the Verbena family. Whatever may be the original home of that ancient tribe which has spread throughout all the temperate and tropical regions of the earth, it is in South America, and especially in the extra-tropical regions, that it has developed the greatest variety both of genera and species. On the heights of the Peruvian Andes, from the snows of the Chilian Cordillera to the shores of the Pacific, as well as on the plains of Argentaria and Uruguay, the botanist is everywhere charmed by the brilliant flowers of numerous species of true Verbena. In the warmer zone the allied genus Lippia becomes predominant, and displays an equal variety of aspect; but in Chili especially we find a number of plants very different in aspect, although nearly allied in structure to the familiar types. The plant of the Rio Colorado—known to botanists as Baillonia spartioides—appears to be rare in Chili, as it is not among the species collected by the earlier explorers of this region.