The New Zealand Plant Conservation Network

Does anyone know of an naturally occurring hybrids between exotic trees and native trees in NZ? I am aware of many herbs (Senecio scaberulus x S. hispidulus etc). and don't need any info on that; I am also aware of native x native hybrids (e.g. Kunzea). I am specifically wanting to know about whether there is any documented examples of a native NZ tree naturally hybridising with an exotic tree. There is one example I can find from overseas of this happening [in an interesting review paper on this subject Schierenbeck & Ellstrand. 2009. Hybridization and the evolution of invasiveness in plants and other organisms. Biological Invasions].

Hi Bec, One i can think of down here in wellington/kapiti is the hybrid between our Native Ngaio - Myoporum laetum, and the introduced Tasmanian relative (boobiala) - Myoporum insulare. There are tell tale signs on the hybrids, such as oil glands (ngaio) are visible, but lacking the dark sticky apical meristem.

of course - I'd completely forgotten about that - a massive issue in reveg on parks here too = thanks.

There's a very curious hybrid in cultivation that is reputed to be Lophomyrtus bullata X a Syzygium species from Australia. Whether this occurred naturally is was a horticultural cross I can't say. A friend's garden near Whanganui has one.

What about Metrosideros hybrids? Aren't there reports of Pacific species crossing with NZ ones (e.g. M. excelsa) spontaneously, as well as M. excelsa X M. kermadecensis? Colin

Thanks Colin - I'll try finding out about the Lophomyrtus cross. I know the Metrosideros cross M. polymorpha x excelsa - was done by horticulturalists as their flowering doesn't overlap usually. But someone else might know of natural ones?

Hi Bec
http://www.doc.govt.nz/Documents/science-and-technical/sfc142.pdf has the following on p.45:
"Caution must also be taken concerning generic and species limits as they are not necessarily well defined as exemplified by the putative garden hybrid between the New Zealand species Lophomyrtus bullata and the Australian Syzygium australe (?Eugeniamyrtus smithi?) (Palmer 1982). Therefore, supposed generic barriers to pathogens may not exist in reality."
Cheers
Colin

I know of no naturally occurring hybrids with our Metrosideros and exotic / naturalised ones. But I do know that M. collina 'Tahiti' was successfully crossed with M. excelsa, and also that Tecomanthe montana was successfully crossed with T. speciosa. As Matt suggests the only obvious common one I know of is Myoporum af.f insulare x M laetum (in Australia you get the reverse). I have not heard of the intergeneric Lophomyrtus x Syzygium Colin mentions - and that one (if true) really surprises me - it seems so very unlikely cytologically speaking (very different karyotypes). However, I do know of Coprosma baueri x C. repens - as a problem on Norfolk Island and at Percy Reserve, Petone, Wellington that hybrid happened when C. baueri (female) was planted near male C. repens. Also Sophora chathamica x S. macrophylla is now common in cultivation, and there are rumors that S chathamica x S. cassioides are appearing in Wellington City.

Thank you Peter. Do you know of nay molecular work on Myoporum - presumably Myoporum aff. insulare and M. laetum are really close relatives?