The flora of the Pitcairn Islands: a review

vascular plant flora of the Pitcairn Islands, south-central Pacific Ocean, is described based on extensive new collections made in 1991 and previously published records. Two vascular plants occur on Ducie Atoll; one (Pemphis acidula) is a new record. Sixty-three native vascular plants occur on Henderson, of which nine are endemic; Canavalia rosea, Operculina lurpethum, Psilotum nudum and Solanum americanum are new records for the island. Oeno Atoll has 16 native vascular plants; the single endemic (Bidens hendersonensis var. oenoensis) was not found in 1991 despite careful searches. Triumfetta procumbens was new for Oeno. Sixty-six native vascular plants have now been recorded from Pitcairn Island, there are two endemic ferns and seven endemic angiosperms in this number. A number of non-native taxa were new to Pitcairn. Some of the previously described taxa could not be found on Pitcairn, probably because they are very rare and only a small amount of time was spent collecting on Pitcairn. Many of the Pitcairn taxa are threatened by the spread of introduced species, especially Syzygium jambos.     

The Foraminifera of the Pitcairn Islands

Foraminifera were recovered from 18 samples collected in the Pitcairn Islands, 12 from Henderson Island (including the best and most comprehensive collections) and three each from Oeno Atoll and Pitcairn Island itself. Although both algae and sediment samples were collected, the living Foraminifera came, almost exclusively, from phytal (attached or clinging) habitats. Foraminifera in the sediment samples are mainly thanatocoenoses. The fauna is an exclusively calcareous, relatively low diversity assemblage, dominated by large soritids [Marginopora, Amphisorus, Sorites) and Amphistegina , all of which are ubiquitous throughout the tropical Pacific. These larger Foraminifera are usually accompanied by small miliolids in particular, as well as by small attached Foraminifera (discorbids and the like). Typical reefal Foraminifera are generally under-represented. So far, no endemic species have been found. Of more significance, perhaps, is the apparent absence of Calcarina , small rotaliids, elphidiids and agglutinating species, so common in the western Pacific islands. One sample of fossil Foraminifera was analysed, from a shelly sand (c. 30 m above present sea-level) on Henderson Island. Though, for the most part, like the Recent assemblages, this was characterized by Archaias , a soritid which was not found in any of the modern collections made by the 1991– 92 Expedition. This could either be a sampling artifact or refer to a real environmental change since the Pleistocene.