XXVII ELATOSTEMA 405 



mode of dispersal. My experiments in Fiji show that neither the 

 drupe nor the stone of this species floats in sea-water ; and it is 

 probable that the fruits of this genus referred to by Mr. Hemsley 

 as having been picked up on the beach in the Aru Islands 

 possessed only a temporary buoyancy. 



This genus presents us with the same puzzling question put to 

 us by several Fijian genera, such as Myristica and Podocarpus, 

 that occur in both Asia and America ; and until we answer that 

 query it seems almost futile to study modes of dispersal. 



Elatostema (Urticaceae) 



This genus of annual and perennial herbs belongs to the 

 tropical regions of the Old World. It is represented in Samoa by 

 fifteen known species and by at least four or five in Fiji, whilst 

 with the exception of a solitary Tahitian species it is not recorded 

 from East Polynesia. Reference is here made to it particularly on 

 account of its great development in Samoa. We have here a 

 genus that, like Psychotria in Fiji and Cyrtandra in Fiji, Samoa, 

 and Hawaii, runs riot in respect to the production of species (see 

 p. 317). Dr. Reinecke describes fifteen Samoan species, of which, 

 with the exception of two found in Malaya, all seem to be 

 described for the first time. So sensitive, he remarks, is the genus 

 to external conditions that station-forms abound ; and he points 

 out that if we were to follow the dividing lines usually recognised 

 between species, we should account every station-form a 

 new species. It is, of course, obvious that the polymorphism 

 of the Samoan Elatostemas depends primarily not on the varying 

 influence of station but on their sensitiveness to external con- 

 ditions. One might put the question to the Samoan Elatostemas 

 that Hillebrand put to the Hawaiian Cyrtandras, and ask why nature 

 in this particular genus in this particular locality thus luxuriates in 

 formative energy. Almost every Pacific group in respect of some 

 of its plants presents the problem so well stated by Dr. Reinecke 

 for this genus in Samoa. It is noteworthy that Schimper, in his 

 work on Plant-Geography (English edition, pp. 291, 297, 299), 

 especially singles out Elatostema and Cyrtandra as growing 

 socially in the tropical rain-forests of Java and of the Asiatic 

 mainland. 



Scirpodendron costatum (Cyperacese) 



As far as I can gather, this giant-sedge has not been previously 

 recorded from Fiji ; but it is included in the Samoan flora, and has 



