The Flute Lichen is easy to recognise with its hollow or inflated thallus perforated with holes (like a flute). The other two species with a hollow thallus are Hypogymnia tubulosa and H physodes. They have larger lobes than the Flute Lichen and do not have holes. They are both much commoner than the Flute Lichen and one or other of them will often occur with it.
The Flute Lichen normally occurs in damp shady woods on acid-barked trees such as Birch, Alder and young to middle-aged Oak (older Oaks are more alkaline). It is important to record it where it occurs as it’s an indicator of ancient woodland. We are all familiar with the many ancient woodland indicators that occur in our area on Hazels and other alkaline-barked trees, but in birchwoods there are not so many and this perhaps the easiest one to look out for.
Apothecia or “fruits” are very rare on this lichen and I have never seen them. It normally reproduces by means of soralia, rounded heaps of powder on the ends of the lobes or on the lobe surface, sometimes on short stalks, as seen in the pictures above.
The lichen is a pale bluish grey when dry and greener when wet. The underside is black, and does not have any rhizines, the root-like underside growths that occur on the common non-inflated blue-grey lichens such as Parmelia, Hypotrachyna and Parmotrema species. The lobe tips are often dark brown where they begin to turn under, as in this photo.
M terebrata is a hyperoceanic species virtually unknown in Britain away from the west coast. It has a similar distribution to Hypotrachyna laevigata, which is the dominant lichen on birches in our area but absent further east where it can’t cope with the drier conditions. M terebrata is even less tolerant of any reduction in rainfall than H laevigata. You’ll see an awful lot of H laevigata while looking for M terebrata. It’s quite easy to pick out the hollow-looking lichens from the flat Hypotrachyna and Parmelia around them, but the first hollow ones you find will probably be Hypogymnia species. Then it’s down to finding one with holes, and you’ll know you have a genuine Flute!
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