74 



C. SKOTTSBERG 



majority of our basic angiosi)erm groups, but that also it has been on these same southern 

 land masses where the greater part of their primary evolutionary divergences took place 

 (pp. 180-181), 



and he continues, 



It seems likely that the angiosperms, as a group, arose on this southern land mass 

 contemporaneously with the Paleozoic of the northern (Holarctic) land mass and that 

 the divergences of the basic, generalized familial groups had been accomplished in this 

 southern hind mass certainly by the mid-Mesozoic. 



This would make the Jurassic the great period of ascendency of the angiosperms. 



C'ami's theory does not, at least at first sight, agree too well with his opinion 

 on the origin of the Magnoliales, always regarded as a primitive group though 

 not of restricted range; the Winteraceae have a stronghold in New Guinea-Australia- 

 Xew Zealand, and the actual distribution of this family testifies to a southern origin. 



Recently SlKHBlNS (^57) took up the question of the history of the Ranales. 

 He points out (p. 8) that this order » 



includes a high j)roj)ortion of sj)ecies which on the basis of all characteristics must be 

 ])laccd not only in monotypic genera but even in monogeneric or digeneric families. 

 Thcv are obviously relict types of which the close relatives have long been extinct. . . . 

 Finally, distributional studies show that the genera and species are at present strongly 

 concentrated in eastern Asia and Australasia, and at least one family, the Winteraceae^ 

 may have radiated from the latter center (A. C. Smith 1945). This family was dispersed 

 through the Antarctic regions. 



We cannot deny^ the possibility that New Guinea was the birthplace of types 

 that now generally pass as Antarctic, a theory first advanced by Miss GiBBS (lod) 

 and perhaps strengthened by the sensational discovery there of a great number of 

 Xothofagus species, but it is quite clear that, if they are bicentric, they must have 

 migrated across what is now the Antarctic continent in order to arrive in S. America 

 which again com[)els us to assume that connections were established on both sides, 

 and the existence of fossil plants belonging to taxa now living in the two sectors 

 furnishes additional evidence that Antarctica took an important part in their history. 

 Anyhow, Xothofa^i^iis survives in greater variation in New Guinea than either in 

 New Zealand or in Chile, though these are situated nearer to the Antarctic continent. 



Before Antarctica was recognized as a possible centre of evolution, the Holarctic 

 region was claimed as the great and only cradle of temperate plant families which 

 s{)read soutii during the Tertiary just as, in pre-Tertiary times, tropical families 

 had extended to the j)rcsent Arctic. GoRDuX (77?), although he finds undeniable 

 proofs of an old Antarctic radiating centre, carefully scrutinizes the possibility of a 

 northern origin of temperate types now found in the south, referring to Oliver's 

 theory that :i genus like Xothofagus originated in \. America and that two tracks 

 lead sf)uth, one to subantarctic America, one across the Ikring land to Australia 

 and Xew Zealand, but he doesn't think it probable that we can explain the dis- 

 junctions of numerous taxa in the south in this way and that the chances for cool 

 climate types to cross the broad and well-stocked tropical belt must have been small. 



To me it would seem more acceptable to fall back on an ancient pantropical 



