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And no, I’m not talking about triffids here. More a part of the continuing series on plant root adaptations. I’ve mentioned mangroves in passing before (to do with their pneumatophores), but the thing that stood out for me about the mangroves we saw in Queensland was the fact that they looked like they were on stilts:

mangroves at low tide.JPGThese trees looked quite different from the familiar NZ mangrove. Mangroves here belong to a single species, Avecennia marina, which is found around the coastline of the top third of our North Island (reaching its southern limits – linked to average daily temperatures - in Kawhia & Ohiwa harbours). A.marina is just one of a group of species grouped under the name ‘mangroves’ (around 30 different species in Australia), characterised by their habitat as much as anything: they grow in muddy intertidal zones along coastlines & in estuaries. That is, ‘mangrove’ is an ecological rather than a taxonomic classification. ’Our’ mangrove differs from the ones we saw over the ditch in that ‘theirs’ have those rather wonderful stilt roots.

Well, some of ‘theirs’ do. It seems that mangroves can be put into 3 groups: ‘red’, ‘black’, & ‘white’ mangroves. The ‘red’ mangroves grow closest to the water and put down stilt-like ‘prop’ roots, like the ones shown above. ‘Black’ mangroves – belonging to the genus Avicennia – put up pneumatophores to allow them to obtain oxygen from the atmosphere. They tend to grow inland of the ‘red’ trees. "White’ mangroves grow even further inland & don’t usually have either type of specialised roots.

I learn something new every day :-)