Species of the Month - January 2013
Willow Jelly Button & Birch Jelly Button
Exidia recisa Exidia repanda
These are small jelly fungi about 1-2 cm across which are found on willow and birch twigs respectively, usually in the winter months. January is probably the peak month for seeing them. They are invisible after a spell of dry weather as they shrink to a thin film over the twig, but they swell up again as soon as it rains and remain that way for some time afterwards.
pictures above show Willow Jelly Button, and those below
are of Birch Jelly Button. Both species seem quite common in our
area compared to the rest of the country, or perhaps it's just that
they're more visible here because of all the rain we get. The
Birch Jelly Button tends to have a flatter fruitbody while the Willow
one often hangs down from the twig, but they can be safely told apart by
their host tree alone. There are no microscopic differences
fungi usually grow on dead twigs attached to live trees.
They break down the wood of the twig and feed on it. Thin dead
twigs high up in a tree dry out very quickly which is why the fungi have
developed the ability to swell up and store water whenever they get the
They can sometimes also be found on fallen twigs on the ground
underneath the tree.
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4 Jan: Chris Irvine found both species near Kinlochleven.
9 Jan: I found Willow Jelly Button at Inverawe, on what appeared to be Grey x Eared Willow
10 Jan: I found Willow Jelly Button on Grey Willow at Airds Bay, photo below
These last two photos clearly show how the Willow Buttons are droopy while the Birch ones are more button-like.
14 Jan: Robert Macpherson found Willow Button on Eared Willow, and Birch Button on Downy Birch, both at Ganavan.
20 Jan: After a spell of dry
weather, Jan went back to the site where she took the above photo, and
managed to locate the buttons in their dried-out form. These are almost
impossible to spot unless you know where they are.
The one on the left has not dried out completely but on the right you can see how they eventually reduce to a dark skin over the twig. Even though Jan knew where they were, she thought at first that they had all disappeared.
Note you can still send in records for past species of the month. Here is the list of species we've had so far:
Dec 2012 - Dice Lichen