Getting to like Lichens

 You have probably noticed that most of the trees in Newtonmore have green growths on them - no, I don't mean leaves!-  but growths that look like miniature bushes or coloured patches.

Lichens on a tree trunk

These are lichens (pronounced either like-uns or litch-uns).  Are they a plant or what?  Most are a combination of two things - a fungus and an alga.  A fungus can't manufacture its food from sunlight using chlorophyll like green plants and algae can. The fungus provides a home for the alga which then manufactures food.

Having been inspired by the lichen talk referred to in my last post, I have been looking more closely at the lichens growing locally. It is easy to collect samples as they often blow off the trees.  I have bought a leaflet by the Field Studies Council "Key to Lichens on Twigs" so I can have a go at naming what I see. There are lots of photos and a simple multi-access key (where you tick what you can see and it suggests the name). A similar key (but no photos) is available online at the Natural History Museum.  

There are also 2 free sheets of information and photos of the 20 most common lichens available from The British Lichen Society.

So here is a lichen that I picked up off the ground:

Lichen from the top

The first decision is to look at how it grows (pictures from NHM site):

fruticose  Branched shrub-like lichens attached to the twig by a sucker-like holdfast.

foliose  Leaf-like lichens attached to the twig by the lower surface.

crustose  Crust-like lichens that are only removed by cutting the bark.

It is like a little bush that was attached to  the tree at one point - which is more obvious when you look at the underside, as the branches come from a central point:

Lichen underside

So that makes it a bushy or fruticose lichen.

The next decision is whether the branches are the same colour on top as underneath.

Top side - light green

Underside - whitish

So the top and bottom surfaces are a different colour.  That makes the ID easy as there is only one fruticose lichen on my leaflet that has different colours on each side, Evernia prunastri. The leaflet says that the branches should be flattened in cross-section which is true as well. It is also known as Oakmoss which is not that helpful as it isn't a moss, and mine wasn't growing near an oak. Another name is Stag Lichen which does match the antler-like shape of the branches.

I could not smell anything much from my sample, though Encyclopedia Brittanica says this:

"Oak moss was used in perfumery as early as the 16th century. Baskets filled with it have been found in the ancient royal tombs of Egypt, but whether it was intended for perfume or for food is not known. Oak moss contains a starchy edible substance. A mixture of acids extracted from it is used in drugs for treating external wounds and infections."

It is very common locally so keep an eye out for it next time you are out on a walk.