Rapa Nui Shrubby Aster (Asteraceae gen. & sp.)

At least six (!) different types of Asteraceae pollen are known from Easter Island’s deposits, most of which were recovered from the Rano Aroi crater at the Ma’unga Terevaka volcano, the largest and tallest of Rapa Nui’s volcanoes. This material, however, can only be assigned to a tribe within the family Asteraceae, to the Tubuliflorae, now known as Asteroideae, a group that is represented in the Polynesian region mainly by the very large genus Bidens.

This genus occurs with as many as at least 59 species, subspecies and varieties all over central, eastern and northern Polynesia. The place closest to Rapa Nui, the Pitcairn Islands, harbor at least two endemic species, the Henderson Island Beggarticks (Bidens hendersonensis Sherff) and the Pitcairn Beggarticks (Bidens mathewsii Sherff). Thus, it is absolutely possible that additional species also once inhabited Rapa Nui.

It appears that this species, or these species, disappeared quite recently, maybe shortly before the island was discovered by European seafarers. [1][2]

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References:

[1] J. R. Flenley; Sarah M. King: Late Quaternary pollen records from Easter Island. Nature 307: 47-50. 1984
[2] J. R. Flenley; Sarah M. King; Joan Jackson; C. Chew; J. T. Teller; M. E. Prentice: The Late Quaternary vegetational and climatic history of Easter Island. Journal of Quaternary Science 6(2): 85-115. 1991

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edited: 22.06.2020