Let’s explore the fascinating world of lichens.
The gray, wet weather is perfect for going on a hunt to discover these incredibly interesting species and the lack of foliage makes the rocks, outcrops, shrubs and tree trunks where they grow much more visible.
But first…..what exactly is a lichen? Lichens are a composite organism formed by a symbiotic relationship between a fungus and a photosynthetic partner like a green alga or a cyanobacteria.
Say what!? Basically, its fungi that instead fo invading or scavenging for nutrients, cultivate algae/cyanobacteria within themselves. The algae/cyanobacteria provide carbohydrates, proteins and vitamins thru their photosynthesis while in return the fungus provides increased access to minerals and protection from the elements. They work together in a mutually beneficial way.
Fungi don’t photosynthesize so the nutrients produced by the algae/cyano feed the fungi while the main body called a Thalis, which is a structure of Funa filaments (hyphae) protects the inner algal or cyanobacterial cells from intense UV radiation and drying out. Essentially the fungi provide a cozy habitat while the algae/cyano provide food.
Lichen are very abundant. There are 3,600 species just in North America; 20,000 species worldwide. They come in many different shapes, sizes and colors but all lack true stems, roots or leaves. Their classifications are descriptive of their appearance.
CRUST: Closely attached to host, with a hard upper surface.
SCALE: Tiny shell-like lobes usually forming over lapping colonies.
LEAF: Small to large leaf or strap-like lobes – some resemble leaves.
CLUB: unbranched or sparsely branched upright cylindrical stems.
SHRUB: Many branched cylindrical stems, usually tufted.
HAIR: Intricately branched filaments, tufted to a pendent (think old man’s beard).
Lichens are a pioneer species that are able to grow where nothing else can, in cold, barren harsh areas, breaking down bare rocks into the soil to pave the way for other plant life. They can be found everywhere – from deserts to alpine tundra, tropical rainforests, rocky outcrops, grasslands, old growth forests, even in Antarctica!
You’ll find them on trees, rocks, fences, soil, shrubs; just about anywhere. Life spans range from 1-2 years for tropical species to several thousand years in slow growing alpine and arctic species, making them sone of the oldest living organisms on the planet.
They provide food and nesting materials for various animals and birds. A food source for herbivores like elk, moose, caribou and deer, especially in winter when other food is hard to find. Mountain goats and sheep also rely on them as do ptarmigan. Northern flying squirrels use them for both diet and nesting, while hummingbirds line nests with strips of lichen for insulation and as camouflage of the outer nest. Some insects use them as camouflage too, including the giant Lichen orb weaver spider.
Historically, humans have used various species to make dyes and medicines. Native people colored fur, moccasins, feathers, wood and baskets with lichen.
Lichens produce unique biochemicals to fend off predators, prevent freezing and stop germination of seeds in their soft tissue. These chemicals hold promise for development of new medicines an agricultural application. Some have antibiotic properties. In Japan it’s used in paint for its anti-mildew properties.
Lichens absorb water and nutrients directly from the atmosphere and are sensitive to heavy metals and air pollution, making them indicators of environmental health. Because they absorb what’s present in their surrounding atmosphere, scientific extractions of lichen can be used to determine pollutant levels.
Some, like Lungwort (Lob aria Pulmonaria) only grow where the air is pure. Lungwort sickens and dies in polluted areas. Found on both coniferous and deciduous trees in humid forests at low elevations, Lungwort’s greenish large, broad loosely hanging lobes are highly recognizable. Contrary to popular belief, lichens do not kill trees and shrubs, though are often blamed for it. They do grow on slow growing and sometimes declining trees and shrubs but are mostly considered an indication of good air quality. Faster growing trees shed bark before lichen has time to colonize.
During dry spells lichen shrivel and fade and are easily walked past, unnoticed during summer. When re-moistened, by the fall rains they expand and their surfaces become transparent, allowing the alga and cyanobacterial colors to show thru. The wet autumn days five them new vibrancy. Whether it’s the colorful rocks and cliffs painted with the reds, yellow and greens of crust lichens, the long drapes of pale green witches’ hair hanging from the trees on the fluorescent chartreuse of wolf lichen clinging to wood – Lichens are one of the little things that can enliven a walk on a cloudy fall day.
Are you ready to out and enjoy the natural beauty of lichen? Perhaps discover that you really are “Lichen it “by trying to find as many different kinds as you can.