Lichens

Lichens are a fascinating type of life.  Actually, they are two types of life living together in a symbiotic (mutually beneficial) way.  The symbiosis is so strong, that often one partner cannot live without the other.

Fungus is the larger of the two partners.  It provides mineral nutrients and a home outside of the water.

The other partner is either cyanobacteria or algae.  Both plants perform photosynthesis, which forms sugars or carbohydrates.  The fungus eats the sugars or carbohydrates.

Lichens grow on rocks, trees, or on the ground.  They come in three overall forms; crustose, foliose, and fruticose.  Crustose looks like a crust, foliose looks like leaves (think foliage), and fruticose looks stringy.

Lichen Covered Cliff

Rock Tripe (Foliose Lichen), and Reindeer Lichen (Fruticose Lichen)

Smile.  This Concentric Boulder Lichen likes you.  I've walked past this spot lots times, but never noticed the tiny smiling face of this Crustose Lichen until I took this picture.

This Salted Starburst Lichen is in the Foliose category, and is growing on a log.

If an Aspen Tree (Populus tremuloides) is a pioneering species, then the Lichens are the natives that showed up 8,000 - 10,000 years before the pioneers.  They are the first life to come in (after several decades) to an area where there has been a glacier, a hot fire, or a volcanic eruption.  Being part fungus (a decomposer), they break down the rocks enough for moss to take hold.  The moss in turn makes more soil, which allows plants such as rock ferns (Polypodium spp.), grasses, and sedges to take hold.  They continue to make more soil, and eventually shrubs and then trees come in.  In order for a forest to start to grow, you need lichens.

Rock Ferns with Reindeer Lichens

The Rock Fern fronds will spread out in the summer, and the spore sacks (brown areas) will be hidden underneath.

Lichen and Moss.

This Foliose Lichen, Moss, and White Pine (Pinus strobus) needles show forest succession in action.

Lichens are also a sign of good air quality, since they are very sensitive to pollution.  The next time you are out getting some fresh air in a wild place, don't forget to look at the lichens!