Mav 8, 1684.J 



NA TURE 



THE FLORA OF PATAGONIA^ 



THIS work, the joint production of the late Prof. 

 Lorentz and of Mr. G. Niederlein, is a substantial 

 addition to our knowledge of the vegetation of one of the 

 least explored portions of the earth. It forms one por- 

 tion of the scientific results of the expedition into Pata- 

 gonia conducted in 1S79 by General Roca, who has since 

 been elected President of the Argentine Confederation. 

 The Indians who, under thevigorous and stern adminis- 

 tration of General Rosas, had been terrified into inaction, 

 if not into submission, gradually took courage when they 

 had to deal with less energetic opponents. At repeated 

 intervals the wandering tribes, especially those of Arau- 

 canian stock, made destructive incursions through North 

 Patagonia and the south of the province of Buenos 

 Ayres, massacring the white settlers and driving off the 

 cattle. It had long been the declared policy of the 

 Argentine Government to confine the Indians to the 

 region south of the Rio Negro, by establishing military 

 posts at suitable points in the valley of that river ; and to 

 carry out this project was the object of General Roca's 

 expedition. The chief station occupied was Choloechel, 

 a large island inclosed by two arms of the Rio Negro. 

 From thence the upper valley of that river was followed 

 to its junction with a large tributary, the Nauquem. Prof. 

 Lorentz had already returned to Buenos Ayres, while Mr. 

 Niederlein travelled northward to Mendoza. Although the 

 expedition was carried out at an unfavourable season — the 

 autumn and early winter of the southern hemisphere — 

 the authors succeeded in collecting 337 species, of which 

 thirteen are ferns and the remainder flowering plants, in 

 a district which includes only the north-western portion 

 of Patagonia. It is not, however, easy to say how many 

 of the numerous species not hitherto recorded as natives 

 of Patagonia are henceforward to be added to its scanty 

 flora. Many of the species recorded were found in the 

 region lying north of the Rio Colorado, which is generally 

 regarded as the northern boundary of Patagonia, and are 

 not said to spread to the south of that river. Again, as 

 many as sixty-five species of flowering plants were collected 

 in such an imperfect condition that the authors have not 

 been able to assign to them specific names, and many of 

 these will doubtless be found identical with those already 

 known as natives of the country. Further, it must be 

 added that, of twenty plants described as new species, 

 several appear to rest upon slight distinctive characters, 

 which, in the eyes of many experienced botanists, will 

 entitle them to be counted rather as varieties than as 

 altogether new species. 



Making due allowance for these deductions, it appears 

 that we may reckon about 150 species as additions to the 

 meagre catalogue of the plants hitherto known as indi- 

 genous to Patagonia, scarcely 300 in number for a terri- 

 tory more than 1000 miles in length and from 200 to 400 

 in breadth. Apart from the interest felt by the systematic 

 botanist in the special forms of vegetation displayed in 

 each region of the earth, many questions of a more 

 general character are suggested by the study of local 

 floras, and that of Patagonia is especially suggestive. 

 Ever since naturalists ceased to regard the existence of 

 each organism as due to a special and separate act of 

 creation, and have learned that the existing population 

 of each region is derived by descent with modification 

 from earlier races, the influence of geological and physi- 

 cal changes has assumed a paramount importance in 

 regard to all changes relating to the geographical distri- 

 bution of plants and animals. If we seek to understand 

 how the flora of a given region of the earth has come to 

 be what it is, our first business is to inquire into the past 

 history of that region, and to ascertain from what sources 

 the indigenous species may have been derived. With 



1 " Informe Official de la Comision Cientifica .igrciada al Estado Mayor 

 General de la Expedition al Rio Negro (Patagonia) bajo las ordenes del 

 General D. Julio A. Roca." Entrega II. Cotanica. (Buenos Aires, 1881.) 



reference to the special features of the Patagonian flora, 

 the subject was discussed during the past winter at a 

 meeting of the Linnean Society. It was then pointed 

 out that nearly the whole of Patagonia and a considerable 

 part of the adjoining Argentine territory had been raised 

 from beneath the sea-level during the latest geological 

 period, and that the only quarters from which the vege- 

 table population could be derived were either the range of 

 the Andes or the subtropical region now included in the 

 northern Argentine provinces. It was argued that the ex- 

 ceptional poverty of the Patagonian flora is not mainly due 

 to climatal conditions, but to the fact that in the time 

 which has elapsed since its upheaval only a relatively 

 small proportion of the plants of the adjoining regions 

 had been modified to suit the conditions of life in the 

 newly-formed territory. 



It is interesting to see what light is thrown on the sub- 

 ject by the present work, which, although bearing the 

 date 1881, appears to have but very recently reached this 

 country. Our previous knowledge of the flora was nearly 

 confined to the region near the coast, whereas most of 

 the plants here enumerated come from the territory near 

 the eastern base of the Cordillera. Whether owing to 

 the season, or to the fact that they do not extend to the 

 interior, many of the indigenous species known to occur 

 near the coast — at least a hundred might be enumerated 

 — are absent from the enumeration of MM. Lorentz and 

 Niederlein. But a comparison of all the materials acces- 

 sible displays a remarkable degree of uniformity in the 

 general features of the vegetation. When raised from 

 the sea the newly-formed territory of Patagonia was de- 

 pendent for a vegetable population on the immigranc 

 species which it might receive either from the range of 

 the Cordillera to the we 3 t, or from the subtropical region 

 to the north. As a matter of fact the predominant 

 features of the vegetation are derived from the lower zone 

 of the Andes, the majority of the species being either the 

 same or slightly modified forms of plants of that zone. 

 Our knowledge of the eastern slopes of the Andes in 

 Patagonia is so imperfect that we cannot say whether a 

 few apparently very distinct plants, two of which are here 

 described as types of new genera under the names 

 Niederleinia and Grisebachiella, are derived from the 

 higher zone of that range ; but it is remarkable that as a 

 general rule very few of the characteristic plants of the 

 higher Andes should have been able to adapt themselves 

 to the conditions of life on the plateaux of Patagonia. 



The plants of the subtropical region have exhibited 

 greater power of adaptation to new conditions. Of the 

 larger trees none have been able to spread so far south- 

 ward ; and, except where planted and specially protected, 

 it is not likely that they ever can do so. But of the small 

 bushes and perennial herbs which make up the bulk of 

 the flora a considerable number must be reckoned as 

 more or less modified descendants of subtropical types. 

 It is rather singular to note that this power of adaptation 

 seems to be characteristic of certain groups or natural 

 orders. The most marked instance is that of the Legu r 

 minosce. In the Old World the tribes of this family 

 characteristic of the tropics show no tendency to extend 

 into the warm temperate zone, the only exceptions that 

 suggest themselves to the writer being a few acacias in 

 North Africa ; whereas we find in this volume out of 

 twenty-one species of indigenous Leguminosaa ten belong- 

 ing to characteristic genera of the tropics ; including two 

 species of Ciesalpinia and one (new) species of Mimosa. 



The condition of an extensive territory inhabited by a 

 relatively small number of indigenous species, many of 

 them probably but imperfectly adapted to their environ- 

 ment, was evidently very favourable for colonisation by 

 new immigrants ; and the chances in favour of the new 

 comers were further increased on the introduction of 

 agriculture and of domestic cattle from the Old World. 

 The" plough clears the ground from many'bushes and 



