Chatham Islands, New Zealand

At the request of members of the Pitt Island community, DOC Threatened Plant Scientist Dr Peter de Lange and Landcare Research Biosystematist Dr Peter Heenan visited Pitt in the last week of November, accompanied by local DOC employee Ben Horne. The three men under took an investigation of the cultivation relicts and gardens of many of the Pitt Islanders as a further step toward their preparation of a Flora of the Chatham Islands.

The gardens of the Chatham Islands reflect a wonderful history of trading and swapping valued ornamentals and medicinal plants, as well as providing historic and modern links back to New Zealand gardens - often the primary source for Chatham Islands plantings.

At the specific invitation of Pitt Islanders what have been dubbed the "two Peters" and Ben made listings for what each garden contained, and with owners permission collected specimens of plants they could not identify in the field, or which appeared to be naturalising beyond the home garden. Some common patterns of "garden favourites" soon became evident, for example each garden had at least one kind of Fuchsia but most gardens had plants to keep the botanists head scratching, and the origin of at least one, a seeding form of wandering jew (Tradescantia fluminensis) remains a botanical puzzle. So far this seeding form of what is generally considered a notorious but mercifully sterile weed has been found only once before in 2006 at Awatotara. That plant matches two other plants gathered from New Zealand gardens. How it got to the Chathams, let alone New Zealand is a mystery because so far it has not been seen in older collections of the more common sterile wandering jew - a form which has been known wild in New Zealand since the 1890s. Another interesting plant this time, an old fashioned rose growing at Flower Pot, and possibly a descendant from a planting made by Fredrick Hunt doesn't match any other seen on Chatham or Pitt Island and seems to be absent from New Zealand as well. To work that one out may take years.

A presentation was given one evening at the Pitt Island School detailing the botanical history of the islands, describing its special plants from seaweeds and lichens to mosses, liverworts, ferns and flowering plants. Naturalised plants were show cased and issues such as the risk of hybridism between New Zealand native plants and their close relatives on the Chathams debated. Pitt Islanders were presented with DNA based evidence which suggest that some of the special plants of the Chatham Islands flora are between 4.5 and 14.3 million years old. An amazing story of the Chatham Island forget-me-not was unraveled, it being shown that this iconic plants nearest relative is a small herb found in the distant Mediterranean!

Both Peter's noted that currently there are 36 endemic plants (that is plants found naturally nowhere else in the world outside the Chatham Islands) but they believe the figure could be as high as 51 making the Chatham Islands one of the worlds botanical biodiversity hotspots.

All three were delighted with their 3 days field work and the "two Peters" were especially astounded by the kindness shown by the Pitt Island families and their willingness to participate in the survey. This is something that neither man has experienced quite to the same degree back in New Zealand.

During their field work only a few serious environmental weeds were found, and most of these are present at levels that could easily be contained if action was taken soon. Several garden plants established on Pitt are new to the islands, and at the end of their visit they believe that a further 18 records have been added to the growing list of plants believed native or naturalised to the Chatham Islands.