DERIVATION OF THE FLORA AND FAUNA 4 II 



Geographical elements. 



In 1934 I made an attempt to arrange the vascular plants according to their 

 distribution, with the following result (2jg. 278-279, translated from French). 



1. Australian-Polynesian element (12). 



a) Species found elsewhere: Paspalum (2), Sporobolus, Calamagrostis, Dichelachne, 

 Eragrostis, Juncus, Peperomia, Chenopodium, Nasturtium, Erythraea. 



b) Endemic: Stipa horridula. 



2. Palaeantarctic element (3). 



a) Species found elsewhere: Apium, Samolus. 



b) Endemic: Sophora toromiro. 



3. American element (6). 



a) Species found elsewhere: Cyperus vegetus, Scirpus, Polygonum, Lycium. 



b) Endemic: Axonopus paschalis, Danthonia paschalis. 



4. Wide-spread tropical element (10): Cyperus (3), Boerhaavia, Tetragonia, Caesalpinia, 



Euphorbia (2), Calystegia, Ipomaea. 



Going into more detail, I have tried to rearrange the angiosperms in the 

 following manner. 



I. Palaeotropical element. — 22 sp. (70%). 



1. Pantropical (6): Cyperus polystachyus, cylindrostachys and brevifolius, 

 Peperomia reflexa, Boerhaavia diffusa, Ipomaea pes caprae. 



2. Malaysian- Polynesian (9): Paspalum forsterianum and scrobiculatum, Sporo- 

 bolus elongatus, Calamagrostis retrofracta, Eragrostis elongata, Nasturtium sarmen- 

 tosum, Caesalpinia bonduc, Euphorbia hirta and serpens. 



3. Australian-Polynesian (7): 



a. Endemic: Stipa horridula (.^). 



b. Not endemic: Dichelachne sciurea, Chenopodium ambiguum, Tetragonia 

 expansa, Erythraea australis, Calystegia sepium (.'). 



c. Also in tropical America: Juncus plebeius. 



II. Austral-circumpolar element. — 4 sp. (12.9%). 



a. Endemic: Danthonia paschalis, Sophora toromiro. 

 h. Not endemic: Apium prostratum, Samolus repens. 



III. Neotropical element. — 5 sp. (16.1%). 



a. Endemic: Axonopus paschalis. 



b. Not endemic: Cyperus eragrostis, Scirpus riparius, Polygonum acumina- 

 tum, Lycium carolinianum var. 



I am strongly inclined to regard Cyperus eragrostis as a late immigrant from 

 Chile. Lycium carolinianum var. sandvicense is a puzzling case, a form of a 

 North American species but only found in Hawaii, Rapa and Piaster Island. It 

 is a halophyte confined to the beach, but one might expect it also to occur on 

 the shores of California etc., from where it has not been reported. Beach plants 



