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.
|British Soldier lichen|
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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