A new species of tree recognised from the Chatham Islands

A new tree reaching heights of 8m and endemic to the two main islands of the Chathams, Rekohu/Wharekauri (Chatham) and Rangiauria (Pitt) has just been described in the December 2008 issue of the New Zealand Journal of Botany (N.Z...J.Bot. 46(4): 567-583). The new tree, long known to the locals as “Shell Akeake” or “Swamp Akeake” was recognised in September 2007 by Dr(s) Peter Heenan and Peter de Lange while visiting a swamp forest remnant near North Head, Rangiauria. Both botanists have described this species as Olearia telmatica (the species name being taken from Greek, and meaning “of a swamp”). In their paper they show that shell akeake is a close relative of another Chatham Islands endemic the iconic akeake (Olearia traversiorum) – probably the world’s largest tree daisy.

Copse of shell akeake

Peter Heenan recognised the distinctiveness of shell akeake at North Head, Rangiauria (Pitt Island), when he noted that it was flowering in September, when akeake usually flowers in late November – December. During December 2007 and May 2008 several visits to the islands showed that both shell akeake and akeake are widely sympatric, the new tree favouring swamps and akeake better draining soils – especially sand soils. Consultation with islanders soon revealed that they had recognised the distinction years ago. Akeake wood burned better and was excellent for use as fence posts and in buildings because it was so durable; shell akeake had less useful wood which took up to 25 years to dry out, further it’s trunk was always hollow.

Critical study soon revealed numerous morphological differences and these were backed up by the use of AFLP DNA finger printing which showed both species are distinct from each other, and apparently not hybridising. Both shell akeake and akeake are regarded as threatened (rated “Nationally Vulnerable”) due the authors believe, to widespread recruitment failure and loss of habitat. They observed that akeake forest (a distinct vegetation type) and the swamp forest frequented by shell akeake are now close to being functionally extinct on the main islands of the Chatham group. In their paper, the authors also correct the spelling of the species epithet of akeake from “traversii” (singular) to “traversiorum” (plural), this change happened through the prompting of Dr Colin Miskelly who had asked Peter de Lange why akeake, which had been named after both father and son by Ferdinand von Mueller, was widely known by the singular epithet “traversii”. Miskelly’s comment prompted the orthographic name change from traversii to traversiorum because he was correct, Mueller had indeed clearly stated that he had named the tree after both the father (William Travers) and the son (Henry Travers) – something other botanists had simply overlooked or not fully appreciated the meaning of for the last 141 years!

With the formal recognition of shell akeake the total number of vascular plants believed endemic to the Chatham Islands has risen to 36. However, recent field work suggests this figure could rise to 50.

Reference
Heenan, P.B.; de Lange, P.J.; Houliston, G.J.; Barnaud, A.; Murray, B.G. 2008: Olearia telmatica (Asteraceae: Astereae), a new tree species endemic to the Chatham Islands. New Zealand Journal of Botany 46: 567-583.

Flowers of shell akeake

Shell akeake in heavy bud

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Chatham Islands Time

Chatham Islands, New Zealand