Over the past few weeks I've been keeping an eye on a fruiting body of Fistulina hepatica that has been developing near the base of an oak tree in Blackbrook Wood in the Rivelin Valley.
Although by no means rare, it is a very colourful and photogenic fungus. All the fruiting bodies I've come across previously have been well past their best, so I thought I would keep a photographic record of this one's growth.
I first noticed it on 7 August. At that time it was roughly the same size, shape, colour and texture of a fresh apricot (a bit smaller than a chicken's egg).
By 16 August it had started to develop the characteristic shape that explains why the French call it langue de boeuf (ox tongue).
Eight days later it was almost mature and starting to darken in colour. According to Patrick Harding's How to Identify Edible Mushrooms, the fruitbody absorbs tannins from the tree giving it a bitter taste. I wonder if the tannins are responsible for its colour too.
By 30 August, the fruiting body was about 20cm across and beginning to take on the meat-like appearance than gives rise to its English name: the beefsteak fungus.
I'm afraid I won't be able to take any more pictures for a couple of weeks, by which time the fungus will probably look like this.
In case you're wondering, this fungus is edible... but opinions are divided about the best way of preparing it. I found some pictures in Beck York's Flickr photostream that show what it looks like when sliced and cooked.