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C. SKOTTSBERG 



cussed his theories in an earlier paper (2?/) to which I refer. RlDl.EV {20j) called 

 the island endemics "newborn species", admitting that all did not fall within this 

 category but were "epibiotics, relics at the end of their species life . . . unable to 

 reach another suitable spot for their growth". It is noteworthy that so many of the 

 "epibiotics" are Composites, famous among diffusionists for their alleged effective 

 dispersal mechanisms; in Ridley's eyes they are, perhaps, pseudo-relicts. Cain {42) 

 takes more or less the same position: "the relic nature of an endemic should 

 never be accepted without some form of positive evidence" (p. 227); proofs are hard 

 to find, no island cases as clear as Ginkgo or Mctasequoia are known. An endemic 

 inhabiting a strikingly limited area may be a young species that had no time to spread, 

 or it may be too stenotopic, but others are what Cain (p. 230) calls "senescent"; such 

 species occupy a small area, are relatively constant, ecologically of narrow amplitude 

 and show low competitive ability. They are unable to "penetrate the prevailing 

 habitats that are dominated by the typical vegetation of the region" but behave 

 just as stenotopic young beginners. If indeed old and senescent they ought to 

 show some primitive characteristics. According to Cain senescent species con- 

 stitute "an anomalous element in the flora of a given region"; this may be true, 

 for in many instances they survive from an earlier climatic period and are barely 

 able to hold their ground under the changed conditions. Nevertheless there are 

 cases when such anomalous species form the typical vegetation of a certain habi- 

 tat and where nobody would dream of regarding them as young beginners; the 

 '' Robiiisonia assemblage" in Masatierra offers a good example (see 2^1). 



Niunber of species per genus. — We know that island floras contain a fair num- 

 ber of monotypical genera, many genera that are large elsewhere but repre- 

 sented on a given island by a single species, and few with many species, so that 

 the numerical relation between species and genus approaches i and does not 

 exceed 2, and this has been regarded as a good proof that the island is truly 

 oceanic and has been peopled accidentally by waifs and strays. This rule is not 

 without exceptions, among which the Hawaiian flora is the most striking. FOS- 

 BERG, who contributed a chapter on the higher flora to Zimmerman's book (^p^), 

 indicates 83 families, 216 genera and 1729 species of angiosperms. The figure 

 for the genera may be a little too low. With regard to species all depends on 

 the species concept. HiLLEBRAND (307) was conservative; from his Flora Drlde 

 (J05. 136) got the ratio 6.2 : i, but scores of well-marked species have been de- 

 scribed since 1888, and in addition, particularly during the last two or three decades, 

 a large number of taxa that are little more than microspecies; unfortunately 

 no case of apomixis has been found as yet.^ It is difficult to know which way 

 to take out of this maze; neither the role played by hybridism nor the existence 

 of modifications due to environment has been duly considered. Based on FOS- 

 BERG's figures, the relation species : genus is 8:1, and this is not at all what one 

 expects to find in an oceanic flora. Nobody is, I think, likely to disclaim New 



^ Among taxonomists particularly responsible for this alarming increase E. E. Sherff and 

 H. St. John should be mentioned first, but some others have also contributed and the writer 

 cannot plead innocent. Sherff, in addition to numerous new species, has described an endless 

 number of varieties. 



