Background Information
Lichens are beneficial to forests by cleaning air, fixing atmospheric nitrogen , and providing food for forest creatures.
We will encounter two common growth forms of lichens: foliose and fruticose.
Lichens have four main, specialized reproductive structures.
We will encounter two common growth forms of lichens: foliose and fruticose.
- Foliose thalli (body) have two sides with different appearances and structures. The lobes, or feet, attach to the substrate (what the lichen grows on). These lichens have distinct upper and lower surfaces.
- Fruticose thalli do not have distinct upper and lower surfaces, and are more of a 3-D object. This growth form also includes pendulous and stringy forms.
Lichens have four main, specialized reproductive structures.
- Apothecia are disk/cup shaped structures lined with a spore-producing surface.
- Soridia are asexual structures which are powdery to granular containing a photobiont (algae) and a mycobiont (fungus).
- Isidia are asexual structures that are finger-like, branched, or globular projections containing a photobiont wrapped in a cortex.
- Pycnidia are asexual structures embedded in the thallus that produce spores.
Lobaria-lungwort *Click on photos to see enlarged images*
Usnea-old man's beardPlatismatia-rag lichenPeltigera-pelt lichenCladoniaRamalinaHypogymnia-tube lichenPseudocyphellaria-specklebelly lichensAlectoria-witch's hairSphaerophorus-coral lichen |
Lobaria is a very common lichen that grows on trees (epiphyte) in forests.
Some of the species found in the Willamette National Forest are: Lobaria oregana, Lobaria pulmonaria, and Lobaria linita. Lobaria has a large foliose thallus with an upper surface color ranging from green to grey. Lobes are common on the margins of the thallus. The upper thallus usually has many ridges while the lower thallus is covered in fine fuzz (tomentose) with sparse root-like structures (rhizines). The apothecia are reddish brown and dish shaped. Isidia or sordia may be present. These lichens are found on trees, shrubs, rocks, and soil.
An interesting fact about this genus is the thallus contains cephalodia which are structures that contain both cyanobacteria and green algae photobiont.
Usnea can be found at nearly every location within the Willamette National Forest. Some species are found in sensitive locations while others have a wide distribution. Species found in this area are: Usnea longissima, Usnea scabrata, Usnea fragilescens, Usnea flavocardia, Usnea glabrata, Usnea fulvoreagens, Usnea hirta, Usnea pacificana, and Usnea subfloridana
Usnea has a fruticose thallus that can be tufted or pendulous. The branches are round in cross-section. Its colors range from pale green to yellowish. Usnea can be distinguished from other lichens by finding the central cord (axis) underneath the inner and outer layer of the lichen (medulla and cortex). Simply pull the lichen strand apart slowly and watch as the cortex and medulla break away to revel the central cord.
Apothecia are rare for this genus. Isidia and sorida are usually present. Papillae, fibrils, and tubercules may be confused with reproductive structures. These are small modifications on the thallus containing cortex or medullary tissue. Reproductive structures are depressed within the branches. This genus is commonly found on bark or wood.
Platismatia is common in the Willamette Valley and surrounding National Forests.
Species found within the forest are: Platismatia glauca, Platismatia herrei, Platismatia stenophylla, Platismatia lacunosa, and Platismatia norvegica. Platismatia is a foliose lichen ranging from erect to drooping. Some species may be pressed closely (appressed) to the substrate. The upper surface is grayish while the lower surface is black to white in color. There may be a few rhizines on the lower surface.
Pycnidia, soridia, and isidia may be present or not. The broad lobes of this genus can be crinkled and ascending. This genus is found on bark, wood, or occasionally rock.
Peltigera is a beautiful lichen that covers our forest floor. This genus can be found in areas that receive shade and water within the forest. To name a few common species in the Willamette National Forest, there are: Peltigera britannica, Peltigera collina, Peltigera didactyla, Peltigera leucophlebia, Peltigera membranacea, Peltigera neopolydactyla, Peltigera pacifica, Peltigera praetextata and Peltigera venosa.
Peltigera has a foliose thallus with color ranging from grey to green. The thallus size can range from the size of your thumb to the size of a dinner plate. The lower surface is veined, has rhizines, and lacks an outer skin (cortex). The venation pattern and rhizine type are important for species identification.
Some species have isidia, soridia, or lobules, but most species will have apothecia. Apothecia are usually on the tips of the thallus lobes ranging from black, brown, or orange in color. This genus is found growing on the ground, on rocks, or on trees.
Cladonia are so of my favorite lichens. This genus is cute and I feel joy whenever I find them. They are extremely common in the forest. Some commonly encountered species are: Cladonia asahinae, Cladonia bellidiflora, Cladonia borealis, Cladonia cariosa, Cladonia carneola, Cladonia chlorophaea, Cladonia ecmocyna, Cladonia fimbriata, Cladonia furcata, Cladonia macrophyllodes, Cladonia norvegica, Cladonia ochrochlora, Cladonia pyxidata, Cladonia squamosa, Cladonia transcendens, Cladonia verruculosa, and Cladonia verticillata. There are many pictures on the left to show the diversity of this genus and also because they are my favorite.
Cladonia is a fruticose lichens with a squamule base. Squamules are small flakes or scales of the lichen commonly associated with this genus. These squamules can vary in size and in their lobed pattern. The part of the lichen sticking straight up is the fruticose piece of the lichen called a podetia. This podetia can be simple or heavily branched with soredia or squamules. At the end of the podetia will be a cup or tip or the apothecia.
The apothecia of the genus can be many colors from red to brown. Pycndia can be present at the tips of the podetia. These can be red to brown as well. This genus is found growing on many substrates such as soil, peat, wood, bark, and rock.
Ramalina is a genus similar looking to Evernia found throughout the Willamette Valley and Willamette National Forest. Species you might encounter in the forest are: Ramalina dilacerata, Ramalina farinacea, Ramalina menziesii, and Ramalina pollinaria.
Ramalina is a fruticose lichen that can be pendulous or erect. The color of this lichen is similar to Usnea because they share usnic acid in their composition. The branches can be flattened, filamentous, or irregular.
Soredia may be present and apothecia will be at the tips or sides of branches. Ramalina is found on twigs, branches, trucks of trees and shrubs, and on siliceous rocks.
Hypogymnia is a very common lichen in the forest. There are many species in the genus, but the most common species found in the forest are: Hypogymnia apinnata, Hypogymnia canadensis, duplicata, Hypogymnia enteromorpha, Hypogymnia imshaugii, Hypogymnia inactiva, Hypogymnia metaphysodes, Hypogymnia occidentalis, Hypogymnia physodes, Hypogymnia rugosa, and Hypogymnia tubulosa.
Hypogymnia is a foliose lichen that can be appressed, erect, or pendulous. This lichen has inflated lobes that are hollow and between 1-6 mm wide. The thallus is white-grey to brown-grey. Pycnidia cover the upper surface. The lower surface is black with wrinkles and may have a hole at the lobe tip.
Soredia or lobules may be present. The apothecia are brown and urn shaped. Hypogymnia grows on the bark and wood of conifers, and may grow on rock or mossy soil. Since this species is often wind-blown out of the canopy, it is often found on the forest floor.
Pseudocyphellaria is a lichen found in the Willamette National Forest with these species present: Pseudocyphellaria anomala, Pseudocyphellaria anthraspis, Pseudocyphellaria crocata, Pseudocyphellaria rainierensis, and rarely Pseudocyphellaria mallota.
Pseudocyphellaria is a foliose lichen with lobes between 0.5-3 cm broad. The upper surface color ranges from grey to brown with many ridges partitioning smooth areas, or it may have only smooth surfaces. The lower surface color is white to dark brown, hairy, and with a few white or yellow spots. The hairy bottom with spots will help distinguish this genus from other foliose genera. Rhizines are usually present.
Soredia or isidia may be present or not. Apothecia are brown with a margin like the thallus. This genus typically grows on rock and trees.
Alectoria is found in the Willamette forest and valley. This genus has a similar appearance to Usnea. The distinguishing characteristic between Usnea and Alectoria is that Usnea has a central cord. Some species you might encounter in the forest are: Alectoria imshaugii, Alectoria sarmentosa, and Alectoria vancouverensis.
Alectoria is a fruticose lichen. It has an erect, tufted, pendulous, or prostrate growth form. This lichen ranges from yellow to green in color. The branches can be variable from circular to flattened.
This genus has soredia or isidia which are absent in most species. Apothecia are disk shaped on the sides of branches. Alectoria can be found on bark, wood, soil or rock.
This genus has one species that is very common in the forest, Sphaerophorus tuckermanii.
Sphaerophorus is a fruticose lichen with erect tufts or cushions up to 10cm in diameter. The branches are round, solid, and somewhat shiny.
Soredia and isidia are absent but the fine branches can serve as propagules. The apothecia are at the ends of the main branches, spherical, and split open irregularly to show a black spore mass. This genus grows mostly on bark.
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