256 



C. SKOTTSBERG 



Chapter II. 



Sources of the island flora as judged by the total distribution of the 



geographical elements distinguished, with special reference to the 



composition of the Chilean flora. 



I have attempted above to describe the distribution of the non-endemic spe- 

 cies, to state where the endemics have their relatives, if any, and to distinguish 

 a number of geographical elements. Now I shall proceed a little further and look 

 at the matter from a wider horizon. A species was called Chilean because it is 

 found also in Chile or has its relatives in the south Andean flora, or it was referred 

 to a Magellanian group because it occurs only in the farthest south of the conti- 

 nent, and so forth; but in order to know something of the genesis and history 

 of each group we cannot stop here. We shall find that our "Chilean element", 

 Chilean from our insular viewpoint, consists of several types, each with its own 

 distribution pattern. To speak with WULFF [2gi. 203), until now we occupied our- 

 selves with the geographic elements, now we shall try to trace the genetic ones, 

 "species grouped according to their region of origin, thus reflecting the genesis 

 of a given flora". He very properly adds: "To determine the region of origin of 

 a species" — and indeed also of a genus or family — "is often a very difficult mat- 

 ter, requiring a monographic study. . . ." With regard to Juan Fernandez, the ge- 

 netic elements are congruent to W^ULFF's "migration elements". 



I. Angiospermae. 



Of the two species of Stipa, neesiana is distributed from Mexico through the 

 tropical Andes to Central Chile and east to Brazil, Argentina and Uruguay, lae- 

 vissima (Nassella) a typical Andean species; the former is neotropic, the latter 

 Chilean, extending north into Peru and east into Argentina. Almost the same 

 area is occupied by Piptochaetium bicolor, a genus limited to extratropical South 

 America. 



Podophorus is a unique anomaly without known neotropical affinities, as it 

 were, a far-travelled member of an Arcto-tertiary flora, if its affinity with Brachy- 

 elythrimi hits the mark; in Pilger's opinion it sides with McgalacJnie. 



The species of Chaetotropis were referred to the neotropical group — "tropical" 

 not to be taken in a purely climatic sense, because a species included under this 

 heading may just as well be subtropical and even extend into a temperate zone. 



Agrostis masafuerana and the bicentric A. viagcllanica were linked together, 

 but only provisionally, because in a large and world-wide genus like Agrostis the 

 relationships cannot be safely judged without a thorough taxonomic-genetic study 

 of the whole genus. Assuming that PiLGER was right, Antarctica becomes in- 

 volved, and the two species — and probably others as well — should be classified as 

 "Old Antarctic", or, as I now prefer to term them, Antarcto-tertiary (correspond- 



