Notes of a naturalist in South America

by John Ball

FLORA OF THE PERUVIAN ANDES.

The only tree seen at Chicla is a species of elder—Sambucus Peruviana of botanists—not widely differing from the common black elder of Europe.

Along with the numerous allies of the Old-World flora that characterize the indigenous vegetation, it was somewhat remarkable to find, in the upper valley of the Rimac, a number of cosmopolitan weeds, most of them common in Europe, which appear to have become thoroughly naturalized. Most of these, which are also found in the coast region of Peru, were undoubtedly introduced by the Spaniards; but there are a few, such as the common chickweed, whose wide diffusion throughout the world seems to me to be more probably due to transport by birds.

To the botanist, the most interesting features in the Andean flora are supplied by the great family of Compositæ. To this belong nearly one-fourth of all the plants collected by me, and nearly one-third of those found in the higher Alpine region; and, as far as available materials allow me to judge, I believe these to be about the true proportions for the higher parts of the Andean chain. It is further remarkable that of the thirteen tribes into which the 780 genera and 10,000 species of this family have been divided, all but the two smallest tribes—Calendulaceæ and Arctotideæ—are represented in the Andes. To the European botanist, the most interesting group is that of the Mutisiaceæ, which is especially characteristic of the South American flora. Of 420 known species belonging to this tribe, fully 350 are exclusively American, the remainder being distributed through Australasia, and from South Africa to Southern Asia. They exhibit many unfamiliar forms very unlike what we are used to find elsewhere in the world. One of the first plants which I gathered was a tall, straggling climber with pinnate leaves ending in a tendril. I naturally thought of the vetch tribe, but I observed that the leaves were without stipules, and that the leaflets were not articulated to the midrib. Great, however, was my surprise when, on finding a flowering specimen, it revealed itself as a composite belonging to the genus Mutisia.

Next to the Compositæ, the grasses are of all the natural orders the most largely represented in the Andean flora, but with the difference that nearly all belong to genera common to the mountain regions of Europe. The species are indeed different, but the general aspect does not strike the European botanist as presenting any marked features of novelty.

FLORA OF THE ALPINE ZONE.

One further characteristic of the flora of Chicla is the great variety of species to be found within a small area. In this respect it seemed to me to rival the flora of Southern Spain and Asia Minor, which are known to be exceptionally rich in endemic forms. I am, of course, unable to judge whether in this part of the Andes the species are localized to nearly the same degree as in those parts of the Mediterranean region, and it is at least possible that the individual species which I saw crowded together at Chicla may have a relatively wide geographical range. The only social species, in some places covering large patches on the steep slopes, is a lupen growing in dense bushy masses.

Again guarding myself from the temptation to draw positive inferences from very slight opportunities for observation, I may add a few remarks on what I saw of the flora of the upper or Alpine zone of the Cordillera. This appears to be far more sharply defined at its lower limit than that which I shall designate as the temperate zone. In the latter, although the nights are at all seasons cool, actual frost is rarely experienced, and snow never lies on the ground. In the upper or Alpine zone, on the contrary, night frosts recur not unfrequently throughout the year, snow falls from time to time, more frequent in winter—from May to August—but does not lie long enough to provide a season of complete rest to the vegetative organs. To the influence of these conditions we may probably attribute the chief characteristics of the flora. With scarcely an exception, the species of this zone are stunted in growth, rising but a few inches from the surface, but have much developed prostrate or creeping woody stems, or underground rhizomes. Compared with the middle, or temperate, zone, the species generally belong to the same natural groups. Some of the families, however, which are characteristic of the middle zone, such as Loasaceæ, Verbenaceæ, and Solanaceæ, do not appear to reach the higher region.

Of forms characteristic of the Alpine region of mountains in the Old World I observed several; e.g. Geranium, Astragalus, Valeriana, Draba, a saxifrage, and a very small gentian.

To sum up my impressions as to the flora of the western slopes of the Cordillera, I should say that it appears to be naturally divided into three well-marked zones. The lower, or subtropical, extending to about eight thousand feet above the sea, characterized by deficient rainfall, moderate heat continued throughout the year, and a complete absence of cold, the thermometer rarely falling below 50°. The species here mainly belong to genera characteristic of the flora of tropical America, but, owing to the climatal conditions, are limited in number, and do not include groups requiring much moisture.