A Tree Lichen As One of Nature’s Wonders the Host Plant’s

Have you ever wondered why most of the barks in the forest have a greenish mossy-looking surface? It is probably tree lichen.

There are more than 13000 varieties that exist throughout all countries. They are sturdy and adaptable in any place to grow.

Lichens can grow well in various elevations and climates. They withstand hot temperatures in the desert areas and extreme weather in arctic regions.

However, the species will only survive in a limited environment and geographic feature.

Indeed, what is a lichen? Is it a tree fungus, moss, alga, or plant?

To get the correct answers, keep on reading the following article that presents detailed information about the species. Besides, you will know several varieties and everything to know about these organisms.


What is Tree Lichen?

Those green-blue growths that you see on tree trunks and branches are not mosses. They are lichens, they are composed of two or more different organisms.
Tree lichen

Lichens are organisms that have beneficial symbiosis to develop a plant-like vegetative body. They consist of tree bark fungus and cyanobacterium or green alga. The body parts mostly consist of fungal filaments that protect and support the outside surface.

Then, the fungus functions to gather minerals in the air and take in moisture. However, it cannot produce food, so its partners, alga, and cyanobacterium, do this essential process.

They have green pigments for photosynthesis. Thus, the lichens can grow well by feeding on the nutriment.

Moreover, tree lichen does not have roots, stems, or leaves. This organism keeps growing in wet conditions since it can absorb small mineral substances from the wind.

However, the species will be temporarily devoid of activity in the summer season. Unlike other fungi, the lichens only attach their bodies to the bark without feeding on the host tree.

The rhizoids diffuse through the outer surface, so they do not damage the inner parts of the plant. Thus, their filaments will not dwell permanently inside the tissue.

Tree Lichen Identification

Lichens are often found on tree trunks, branches and twigs as the bark provides a stable place to reside to collect needed sunlight, rainwater and materials from the air.
Lichen on tree bark

You can identify the tree lichen from its appearance and features. It consists of three major body parts that include fruticose, foliose, and crustose.

Since this organism does not have stems, a shrubby branched thallus will develop to the base. Indeed, the strands of the tube resemble a beard.

Also, the lobed thallus has a flat shape that looks like leaves. The foliose is attached to the substratum. Meanwhile, the other plant-like vegetative body that adheres to the substrate is crustose. Thus, this thin part will closely stick on the bark, soil, or rock.

Furthermore, you might identify the tree lichen by noticing various chemicals that it produces. Different types of habitat are also for the identification of this tiny specimen.

Therefore, microscopic study with a 10x hand lens is useful to determine the taxonomy.

Types of Lichens

There are three major growth forms of lichens: foliose, fructicose, and crustose.
Tree lichen variety

Generally, seven common types of tree lichen live on trees and forests. They provide various colors and distinct shapes and sizes.

Also, their habitat may differ from one to another. A specimen can dwell in small twigs, while others prefer acidic barks.

Ramalina Fastigiata

Ramalina fastigiata usually erect, densely tufted and richly branched, pulvinate, lobes 1-5 cm long, 3-8 mm wide, occasionally becoming lax and pendent, pale- to dull grey-green.
Ramalina fastigiata

The cartilage tree lichen has a botanical name as Ramalina fastigiata. This organism features swollen branched lobes that have compact growth.

Besides, its long thalli resemble a strap. It looks green when the environment is wet, but the real color is grayish-green or pickle shade.

As the lichens establish a colony earlier, they may stick on young trees. Likewise, you mostly find them on the twigs in any sunny area. Then, these organisms are commonly spreading over the UK.

Ramalina Farinacea

Ramalina farinacea is an epiphytic bushy shaped lichen common to areas with Mediterranean, subtropical, or temperate climates.
Ramalina farinacea

The ramalina farinacea is another tree lichen that grows around the UK. The species also has strap-like fruticose.

They come in various green shades like silvery pickle and olive. Also, its branch-like parts are narrow and flat. Interestingly, this variety can thrive in both sunny and partial shaded areas.

Xanthoria Parietina

Xanthoria parietina is a foliose, or leafy, lichen. It can be found near the shore on rocks or walls, and also on inland rocks, walls, or tree bark.
Xanthoria parietina

Due to its bright hue, Xanthoria parietina has a common name as an orange or yellow scale. This striking tree lichen also appears in a grayish-gree color in a shaded location.

Generally, it colonizes on old trees, wooden fences, roofing tiles, and inland or coastal rocks.

Hypogymnia Physodes

Hypogymnia physodes is a lichenized fungus within the Parmeliaceae family that commonly occurs in Europe and in many other parts of the world.
Hypogymnia physodes

This species is famous as the monk’s hood tree lichen that has grayish-green swollen lobes. It likes growing on host plants with acidic barks.

Its margin on the base surface comes in a brown hue. Similar to other varieties, Hypogymnia physodes cannot resist Nitrogen and other air pollution.

Physcia Adscendens

Physcia adscendens is a pale grey foliose lichen composed of narrow, flattened branches where the lobe ends become inflated and hood-shaped.
Physcia adscendens

This physcia adscendens is more resistant to Nitrogen pollution than other varieties. Thus, this widespread tree lichen spots on many plants that grow in Nitrogen-rich ground.

This species features a swollen shape on the tip of the lobe that resembles a hood. It comes in pale gray with flat branched thalli. Therefore, they can hold the outer surface tightly.

Candelariella Reflexa

This lichen has small, sometimes continuous, granules that become covered in bright yellow soredia giving it a fluffy appearance.
Candelariella reflexa

The tree lichen that has a fluffy look is Candelariella reflexa. It comes with bright yellowish-green particles.

Then, this common organism usually grows on the lower part of the trunk. Besides, its colony spreads over many plant varieties.

Usnea Subfloridana

Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless.
Usnea subfloridana

The usnea subfloridana is a bushy tree lichen that comes natively from the UK. The old man beard features a black base with grayish-green or yellowish-green thalli.

This variety prefers dwelling on small branches of trees that have acidic barks. Also, it adheres to the birch trunks and twigs.

Lichen Reproduction

Lichen components are a fungus and a green alga with perhaps a blue cyanobacterium.
Lichen on tree

Since the tree lichen is a partnership between alga and fungus, its reproduction might be confusing. The propagation that involves two or more species includes vegetative, asexual, or sexual.

The cyanobacterium does not have a noticeable reproductive organ, so it cannot reproduce sexually.

Otherwise, the fungus has a sexual organ with sacs. They are pouches that contain millions of spores. Yet, new lichens will develop if the reproductive body contacts the proper alga in the right environment.

Additionally, the spreading process of the organisms uses fungal and algal cells to establish an asexual reproduction.

Meanwhile, when it comes to a vegetative manner, the tree lichen has shred or fragments that will cut off to create new individuals.

Places Where Lichens Grow

The most common natural substrates for lichen to grow are trees, rocks, and soil.
Lichen habitat

Each type of tree lichen can live in a different habitat. The species may dwell on the barks, rusty metals, grounds, and dead woods. However, some varieties can only thrive on specific kinds of host plants or rocks.

Usually, he organisms that spot on the living trunks cannot grow on soils and other surfaces. The lichen on tree barks will initially develop the fast-growing fruticose and foliose before the crustose. It depends on the surface conditions rather than the types of host plants.

The crustose lichens prefer living on smooth barks of the young trees, whereas the foliose and fruticose tend to grow on rough and broken surfaces. Their tiny body size can spread throughout the outer tissue to establish a large cover.

Lichens on Dead Trees

Dead wood is an important habitat feature for lichens in forest ecosystems, but little is known about how many and which lichens are dependent on dead wood.
Lichen on dead wood

The tree lichen is not only growing on living plants but also dead woods. How come? Leaf drops allow more light to expose through the organisms. Thus, they can use the sun to photosynthesize and produce food for them.

Another reason is the dropping leaves can retain humidity. Any locations that provide high moisture and more sunlight will be the proper places to grow the lichens.

Are Lichens Good or Bad for Trees?

lichen is in no way harming your tree, but the presence of lichen may point to an unhealthy or dying tree, caused by other reasons, such as pests or disease.
Lichen picture

The lichens are not bad for trees since the organisms will not harm the inner parts of the bark, but they cause an unpleasant look to the surface.

You can use them as an indicator to know the quality of the air. It is because the species rarely grow in any locations with high pollution.

Furthermore, the tree lichen is useful for the host plant since it will alert if any trouble occurs. For example, this organism will come with a redbud that resides on several twigs. Therefore, its presence is useful to prevent fatal diseases and harmful fungal infestations.

Lichen Benefits

They are a keystone species in many ecosystems. They serve as a food source and habitat for many animals such as deer, birds, and rodents. They provide nesting materials for birds.
Lichen benefit

Besides being an indicator of air pollution and fungal infection sign as we have mentioned above, the tree lichen gives lots of beneficial uses for humans and nature. Many animals like mountain goats, deer, and caribou feed on this organism.

Likewise, the lichens become the material to build the nests of many birds. Several types of organisms are also useful for making antibiotics.

Moreover, people who construct model railroad tracks will use the species as a plant landscape on a small scale.

How to Remove Lichens

Lichen is usually the first type of organism to appear after a natural disaster, such as a fire.
Spotted lichen on tree

The presence of the tree lichen does not injure the host plant, so there is no reason to remove this organism. Indeed, eliminating this species will harm the bark and give access to pests and diseases.

However, homeowners who consider the lichens as harmful fungi that give a bad look to the host plant will tend to get rid of them. There are some ways to remove this organism without damaging the bark.

The lichen removal from trees can be safe by using a fungicide that contains copper sulfate. After that, to prevent new growth in the future, regular pruning is essential to keep the plants in a healthy condition.

To conclude, the tree lichen is a self-sustaining organism that will not absorb the nutrients in the host plants.

Therefore, the species is not necessary to remove from the bark. Although it appears ugly, most varieties are beneficial for humans and provide wildlife values.

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