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Coastal Invader Alert
Oct 20, 2004
Author: Auckland Regional Council

Rhamnus (Evergreen buckthorn), is an aggressive tree which is invading our coastal areas. It has the ability to form dense colonies and smothers young native plants especially pöhutukawa. In the last six years more than 15000 plants have been removed from over 12km of Waiheke Island coastline and control work is about to start on Räkino Island.

Over the next few months Auckland Regional Council will be conducting a Region-wide publicity campaign aimed at finding out the extent of the problem with the long term aim to stop the spread of the plant. The public are being asked to keep their eyes open and to contact ARC if they think they have seen Rhamnus.

Rhamnus is widespread throughout Auckland Region; on Hauraki Gulf islands, along mainland east coast and up to five kilometres inland, and has been found in Waiuku. It is spread by birds, possums and other animals. In the past, people have also cultivated and spread the plant.

It is an evergreen tree that grows up to 10 metres in height. The stout stems have dark brown thick furrowed bark when old, but on younger plants they are pale (often purplish) and thin. It has glossy green, leathery oval shaped leaves that often have serrated or toothed edges and prominent veins, with two small bumps at the base of each leaf.

The flowers are small, pale green, and fragrant, occurring from May to November. They are followed by glossy red berries, which turn black when ripe, containing pale white seeds. Rhamnus usually has separate male and female plants, distinguished by the presence of male (no stigma) or female (stigma) flowers.

The campaign will feature local stories, mail outs, and website coverage. If necessary, staff will visit and confirm identification. Advice on appropriate control methods will be offered, small infestations may be controlled and site information will be recorded for use in any future control programme.