Garden Biodiversity Challenge #7

Lovely lichens

Watching spring unfolding in the garden requires patience. Fair enough, if you visit your garden only at weekends, in the intervening few days some things will have happened and changes can be detected. However daily, nay hourly, surveillance of the patch soon presents challenges even for the greatest of nature sleuths, and I certainly would not consider myself one of those. So to keep documenting I have to dig deeper, go the extra mile, step up to the plate, etc, etc, etc,.

There are some things that I accept are beyond my scope of understanding. Things like astrophysics, neuroscience and female intuition. Into this category I would also place lichen identification, for it is devilishly tricky. Lichens are one of these things that are everywhere, right under your nose so to speak, but you never notice them. They are equivalent to the base layers of the world’s great painting masterpieces providing depth, tonal foundation and definition to the natural world all around us. But only the most skilled observer can detect or understand them.

It was into this world that I threw myself for a few days, trying to get to grips with some of the lichens growing in the garden. After all, with the Coronavirus lockdown, I would never get a better opportunity and any exploration of garden biodiversity just would not be complete without reference to lichens. I was ably abetted in my endeavours by the wonderful book Lichens of Ireland written by Paul Whelan, who has done more than anyone else in Ireland to introduce people to lichens and demystify lichen identification.

To give you some sense of just how difficult lichen identification is, it is not even straightforward to say what is a lichen. Lichens are fungi that have formed a relationship with an algae or a bacteria, or both. This relationship is stable and so the forms that grow are distinct shapes and structures which allows clever people to identify them. However, whether these organisms should be classified as lichens or fungi has been a bone of contention for some time, until a scientific truce has been agreed by referring to them as ‘lichenised fungi’.

Lichen are great survivors. The fungal element of the lichen can feed on dead organic matter, whereas the algae or bacteria can photosynthesize, making them extremely versatile and able to grow on a variety of surfaces.  They adorn stone surfaces, tree bark and branches, leaves, soil and they even grow on other lichens. In short, lichens can be found everywhere in gardens.

Lichen generally come in three growth forms. Those that grow directly on the surface of a structure and look to be part of that surface are called ‘crustose’ lichens. Those that grow flat on a structure but have a distinct upper and lower surface of their own are called ‘foliose’ lichens.  The third group are those that grow like shaggy beards on trees, or have fruiting bodies like golf tees, are called ‘fruticose’ lichens. There is no shortage of lichens to find and study, for well over 1,000 different lichens have been described for Ireland. I thought I should at least be able to find and introduce you to a few from my garden. But I should issue you with a health warning, lichen identification is not for the faint-hearted. There is a good reason why there are so few lichenologists in this world; there are not that many clever people out there.

Lichens are not difficult to find, it just involves looking at things very closely. If you notice different blotches of colour on stone walls, you are looking at lichens. If you notice map-like patterns on the smooth bark of trees, you are looking at lichens. If you pry into cracks and crevices of branches and notice subtle textures, you are looking at lichens. Check any fallen branch and it will be covered in lichens. Finding them is the easy part; finding what they are called is an entirely different matter. But here are a few that I found in my garden; I can only hope that I identified them correctly.

Species #23 This foliose lichen is called Xanthoria parietina and is extremely common, covering most dead twigs in our hedgerows. The yellow-orange can be seen from quite some distance, but it tends to be a paler grey-green where it grows in the shade.
Species #24 This one is called Parmotrema perlatum, a common foliose lichen growing on some of the older trees of the hedgerow. Its common name is ‘black-edged leaf lichen’.
Species #25 This is one of a group of about 57 species of Lecanora lichens found in Ireland. It is a crustose lichen. I am taking a punt that this is Lecanora carpinea because of the creamy brown circular fruiting bodies (called apothecia) with the white rim. Another very common lichen on old branches.
Species #26 This is one of the fruticose lichens I found on a branch that had fallen from a tree. It has cool golf tee shaped fruiting bodies. It is a species of Ramalina, possibly Ramalina fastigiata.
Species #27 And here is a lichen growing on the gate post. Which one it is? I haven’t a clue.