Thursday, November 3, 2016

A Reader Said (26)

A reader emailed me to express her disappointment that London Plane (Platanus x acerifolia) is still being planted in Perth. 


I thought I'd share my reply.


Hi __________


Yes, Planes create some allergy issues for some people but to completely ban them is not the answer because they perform a role in cities that no other species can. 

A recent study by Sydney University concluded that the allergy aspect of Plane pollen is overstated and that people are blaming them when the culprits are more likely to be grasses and other species.

Yes, the spiky hairs (trichomes) can be unpleasant if ingested in quantity but that doesn't happen too often and the extreme reaction you refer to wouldn't be normal I wouldn't think.

London Plane is the dominant CBD species in most major cities around the world and interestingly I don't see them pulling them out. Paris is in fact planting more.

I think the answer (as always) is horses for courses. In some situations there is literally nothing that will do the job Planes do and we should take advantage of that.

A good mix of trees - native and non-native - is the way to go for a healthy, resilient urban forest and Planes will always be a component of that.

Regards,

Grayden


Click photo to enlarge 

This is Bryant Park in Manhattan. It has double rows of large London Planes on three sides. That's a LOT of Plane trees. And the park is probably the busiest in New York after Central Park. Whatever allergy issues these trees cause, it certainly 'aint fazing those crazy Noo Yawkers!



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Footnote: I'm highly allergic to WA Peppermint when it's in flower - so are plenty of other people apparently - but I certainly wouldn't advocate abandoning them either.

2 comments:

  1. Many people see the most obvious tree or plant in flower and assume that is what causes the allergy. Some see bottlebrush in flower when also the Cape lilacs and Agonis are. (which I am quite clearly allergic to, can tell by the smell). Re Planes, disturbing them while in flower by pruning etc is said to exacerbate their irritant properties. An oft used excuse to not use Planes is their susceptibility to fungal attack, but this is not consistent and there re resistant strains even in Perth.

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    Replies
    1. I've now included the link to the Sydney University study in the post above. The "hairs" (trichomes) that appear on the backs of the leaves in Spring - and can be seen floating in the air where there are lots of Planes - can irritate the throat/eyes depending on the amount you ingest. Arborists who prune the trees at this time of year will often wear masks but they're of course getting massive exposure compared to the rest of us. Bryant Park (pictured above) is kept scrupulously clean which no doubt helps too as it would clean up the leaves (and seed pods) bearing the trichomes during that worst time of year. Probably something we need to do here where we have concentrated populations of these trees.

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