Sunday, October 17, 2010

Birch Bolete

We found this fine specimen of a birch bolete Leccinum scabrum (and numerous others like it) amongst the silver birches on the edge of the golf course at Wylam beside the River Tyne yesterday. This bolete is always found near birch trees because its underground hyphae form a mutually beneficial relationship - a mycorrhizal association - with the roots of the tree. The fungus helps the tree absorb essential minerals like phosphorus from the soil in exchange for some of the sugars that the tree manufactures.
What I find most remarkable about toadstools is the way in which that mass of diaphenous, microscopically fine underground hyphae come together to form these wonderful three-dimensional structures. How do all those simple threads communicate and collaborate to form the stipe, the cap and - most remarkably of all - all those pores through which the spores are shed? Where does the control centre for this self-assembly process lie? Botany text books can describe with great precison how plants control their development via highly organised growing points (meristems) to produce roots, shoots, bramches, flowers and leaves but the way in which toadstools are built is much less well understood.


The gills under a toadstool's cap (or in this case the pores) must always remain perfectly parallel to the force of gravity if the spores that line them are to drop down and escape into the airstream. Displace a toadstool from the vertical and the gills will realign with gravity very quickly. The process is slower in polypores like this (and they have stouter stipes to keep them vertical) but they still adjust their growth to realign vertically.

It seems to me that a complex toadstool is one of evolution's most amazing, least celebrated, and poorly understood achievements...

14 comments:

  1. This is a whole lot more interesting knowledge that's all new to me. Thanks.

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  2. Yes, so intresting .. much is revealed here, much is learned. Well done
    Greetings..

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  3. Fascinating, Phil, thank you, especially about the caps straightening to maintain alignment with gravity. It interests me too that this is a polypore(?), like the Birch Polypore I've recently pictured(?). The cap in your middle picture has very much the same structure, except it's a free-standing example and not a bracket.

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  4. There are some things we just accept without wondering how, or why. I've never thought of how or why with regards to toadstools, until you mentioned it.
    I want to know the answers now.
    Your posts are always educational Phil, but most of all, always enjoyable.
    Thank you.

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  5. Don't know if you caught this Phil but there was a good general piece on fungi for anyone wanting to get the basics, on BBC Radio 4's 'Saving Species' programme a week or two back go to http://www.bbc.co.uk/programmes/b00rt8qq and the piece is 11.5 mins into the programme).
    The speaker - a decompositional ecologist by trade (cool or what!) talked about 'mycelial cords' where the individual microscopic hyphae clump together underground into thick visible strands. Maybe this is the precursor process to forming the fruiting bodies??
    Allan

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  6. Hi Adrian, the fungi really are a mysterious kingdom..

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  7. Greetings dejemonos sorprender...........

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  8. Hi Emma, I imagine the bracket polypores, with their secure attachement to trees, are less lively to suffer from pores that move out of alignment with gravity - unless the tree begins to tilt

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  9. Thanks for your kind sentiments Keith - hope all is well with you...

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  10. Hi Allan, I missed that programme. You can sometimes find spectacular mycelial cords - looking like a network of black bootlaces that branch and rejoin, under the loose bark of trees that have been killed by honey fungus. What tells those cords that now it's time to change their pattern of growth and work together to become a toadstool...?

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  11. Yes, intriguing question Phil. But alas, fungi aren't sexy (how's that for today's deep thought?) so who's going to fund research to answer questions like that anymore?

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  12. Who indeed, Nyctalus. The last bastion of mycology seems to be the Royal Botanic Garden Edinburgh, which has just published a fantastic new book on these wonderful organisms - see http://www.fromanotherkingdom.com/book.htm and has a major public exhibition on at present

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