Friday, November 20, 2015

Lichen-looking leaves me liking lichens

Foliose lichens

Lichens are an odd lot. They look sort of greenish and make their own food using sunlight, but they don't have flowers or leaves or roots. So they're not plants. They are a composite of two organisms: fungi and algae. Usually the algae is sandwiched in between layers of the fungi. They have a symbiotic relationship - both organisms benefit. The algae make food, and the fungi provide the structure and help retain moisture.
Fruticose lichen - bushy appearance

You'll find them everywhere - from the highest rocky tops of mountains to the rainiest rainforest. You may have seen crusty lichens clinging to rocks - they are the first colonists and secrete acids that gradually break down the rock surface, helping soil development. But it takes time; lichens grow really really slowly. A fast-growing lichen may add 1/2 inch a year.

Trumpet lichens
 Lichens will grow on just about anything that holds still long enough for it to attach to: tree trunks and branches, gravestones, old farm equipment, wooden picnic tables ... even sand dunes. If the sand is stable for a long enough period of time, a soil crust of lichens can form. That allows other communities of plants to move in and establish themselves over the top.

British Soldier lichen
Lichens do more than help the soil; they provide food for animals and insects, and birds use them in nest-building. People use lichens, too. Some lichens are used in dyes. When mixed with pine sap or urine, or burned to ash, they produce a range of colors from yellow to purple and reds. Some lichens are edible, used as food or to flavor food.

You might find lichens in your bathroom cabinets; lichens are used in toothpaste, salves, perfumes and deodorants. Some lichens produce chemicals that inhibit the growth of neighboring lichens - and scientists have found uses of lichen chemicals in herbicides as well as medical applications.

So what's not to like about lichens?
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1 comment:

Rosi said...

Absolutely fascinating. I learned so much from your post. Thanks!