The ‘Green Cancer’
Actually, the Miconia (Miconia calvescens DC.), occurring naturally from Central to South America, is indeed a very beautiful plant – actually.
Unfortunately it is also probably one of the most invasive plant species at all, the worst thing, that could happen to the native flora of many of the Polynesian islands.
The species was brought to Polynesia for the first time in the year 1937, namely to Tahiti, to enhance the inventory of the local Botanical Garden.
Birds, alien species as well introduced by humans like Red-vented Bulbuls (Pycnonotus cafer L.) or Silvereyes (Zosterops lateralis Latham), very soon begun to ensure the dissemination of the numerous, very small seeds. The seeds are also often hidden in the soil adhering the roots of several other plants, for example food plants like Taro, and can, together with these plants, be transported from one place to another. Moreover, they can very easily and absolutely unintentionally be distributed with the muddy filth in the profile of the sole of a shoe.
The species grows extremely fast, its leaves are giant and soon block the light from the smaller plants, which leads to their unavoidably death. Once the species has established itself somewhere, it will soon vehemently assume command over all of the other plant species and generate giant pure stands. For example, in the year 1996 two-thirds of the vegetation on the island of Tahiti were made solely by Miconias (!).
In the meantime the species can be found on several of the Hawaiian Islands (Hawai’i, Kaua’i, Maui, O’ahu), the larger of the Society Islands (Mo’orea, Ra’iatea, Taha’a, Tahiti) as well as on some islands of the Marquesas (Fatu Hiva, Nuku Hiva).
 Jean Yves Meyer: Status of Miconia calvescens (Melastomataceae), a dominant invasive tree in the Society Islands (French Polynesia). Pacific Science 50(1): 66-76. 1996
Photo: Kim Starr & Forest Starr; by courtesy of Kim Starr & Forest Starr