Species Of The Week Number 17: Golden Shield Lichen

Lichens are truly fabulous. Also there isn't much colour around at the moment so this Golden Shield Lichen provides a welcome exception.

The first thing to know about lichens is that they are not one organism but two. A lichen is partly a fungus - but the fungus can't photosynthesise (ie it can't turn sunlight into sugar) so it needs help. It gets that help by providing a home for a green algae which does the photosynthesis on its behalf. Together the fungi and the algae make up the lichen.

The algae of our Golden Shield Lichen is called Trebouxia. Trebouxia can also exist by itself - it just doesn't thrive quite so well without its fungal chum. It also gets everywhere and is found in both polar regions as well as in fresh and salt water and in the desert. I bet it prefers Meanwood though.

The second thing to know about lichens is that many are sensitive to air pollution and are used by researchers to help measure air quality. As a rule of thumb, the smaller and less variety of lichens in an area, the more polluted is the environment. Luckily though Golden Shield Lichen is one lichen isn't that bothered - which is probably why it doesn't mind hanging about near Meanwood Road. In fact it is quite keen on high levels of nitrogen and loves nothing more than a bit of seabird droppings, so is even more common at the coast.

The third thing to know about lichens is that they are are old. Like REALLY old. Humans emerged in Africa about 2 million years ago. Lichens have been here for at least 45 million years, one of the very first organisms to colonise dry land.

There are of course way more than three things to know about lichens. Books have been written on the subject. Lots of books. Just in case you are short of some holiday reading.

Posted on January 18, 2023 06:02 PM by clunym clunym


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