Friday, May 15, 2009

Horse Chestnut Traffic Signals


Newly-opened horse chestnut flowers have a yellow spot on the petals, that turns red once the flower is pollinated. More than half the flowers in this photograph seem to have been pollinated, probably by bees seeking nectar that apparently contains a high concentration of sugar in horse chestnut. I recall reading somewhere that this floral colour change is the tree’s way of telling bees not to waste their time visiting flowers that have already been visited and pollinated. The theory was that this works because bee eyes can see yellow but are well known to be relatively insensitive to the longer-wavelength red end of the spectrum. So this is horse chestnut’s traffic light signalling system – conspicuous yellow for ‘proceed’ and inconspicuous red for ‘don’t bother’. I’ve never see any published scientific evidence to back up this plausible but possibly apocryphal story, but with the aid of a decent pair of binoculars it shouldn’t be difficult to see whether the bees do visit the red flowers......

11 comments:

  1. Well I never. I learn something new every day. I must keep an eye on some horse chestnut flowers down the end of my lane as they are only just appearing.

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  2. Well, first off, a beautiful shot of the horse chestnut, and secondly, I never knew any of that. Fascinating stuff.
    I always learn something when I visit here.

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  3. Thanks John and Keith. Have horse chestnuts in your area been infested by the leaf-mining moth that produces ugly brown blotches on the leaves in early summer? It seems to have spread northwards very rapidly since it was first found in London, back in 2002 I think? It hasn't reached the north east yet. There's are article about it at http://www.forestresearch.gov.uk/fr/INFD-68JJRC

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  4. All seems to be well round here at the moment though I see from the 2008 map the problem is not too far away.

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  5. I've not really noticed, to be honest, but I'll certainly have a look when I'm out. A garden I do some work at has a big Horse Chestnut, so I'll check that out on Monday.
    Thanks for the link.

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  6. This set me thinking (as your blog usually does!). Which other flowers leave signs that they have been visited. I came up with gorse (photo at http://standandstare-nyctalus.blogspot.com/) but there must be others.

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  7. Hi Nyctalus, Gorse and broom are certainly interesting examples. I've noticed that white clover florets bend downwards from the main inflorescence after they've been pollinated and often develop a pink tinge but, like you say, there must be others - I'll have to take a closer look!

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  8. I have just discovered your blog and I am loving it! I feel like I am 5 again, lifting stones and poking my nose in flowers etc. to (re)discover all the wonders of the world of DETAIL! So refreshing! The fact that you are a very accomplished photographer of your subjects makes for a very well rounded blog, I'm hooked already! Thank You! I will have to get my sons in on this one, it's a keeper ;)

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    Replies
    1. Thanks for visiting and for your kind comments Michael. All the best, Phil

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  9. your'e welcome phil, it's just so nice to know there are people in the world who care about this sort of thing, especially the miniature world, my youngest one has been fascinated by things of a miniature or small nature from a very young age so you can just imagine how enthralled he'll be when I show him this blog. Sorry haven't had the chance just yet as only just got in, the sad thing about reality is that it does not stop for you. you have to make that time. but i am certainly inspired! and thank you again for the fantastic 3 part tree spotters guide, the first one in colour i have seen and becasue I am a gardener by trade I can tell you I truelly appreciate it! As mentioned before I am hooked! Hope I can be a contibutor of sorts in the not too distant future?! :)
    Michael

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  10. I've already shared your blog on facebook with a friend of mine who had posted some fab pics of a nature walk they did so all the signs were there for someone whom I know will appreciate you Cabinet of Curiosities as much as I do!

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