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Spot tests on the foliose lichen Punctelia borreri showing thallus (top) and medulla (bottom). The pinkish-red colour change of the medulla in the C and KC tests indicate the presence of gyrophoric acid, a chemical feature that helps to distinguish it from similar species in the same genus.
With the exception of calicioid lichens, lichen growth forms are based on the appearance of the thallus, which is the vegetative (non-reproductive) part of the lichen. [5] In most species, this form is determined by the lichen's fungal partner, though in a small number, it is instead the alga or cyanobacteria (the lichen's photosynthetic ...
Study of lichens draws knowledge from several disciplines: mycology, phycology, microbiology and botany. Scholars of lichenology are known as lichenologists. Study of lichens is conducted by both professional and amateur lichenologists. Methods for species identification include reference to single-access keys on lichens.
Some species, the lichenicolous lichens, can even develop their own lichenised thalli using the host lichen's photobiont. [8] Certain lichenicolous fungi may play important roles in nutrient cycling within the lichen thallus, potentially benefiting the host by degrading and recycling older parts of the lichen.
Arthonia radiata is a crustose lichen with an immersed thallus, often separated from its surroundings by a thin brown line.The thallus is typically pale, ranging from white to pale grey, sometimes with a brown or olive tinge, and often forms a mosaic-like pattern on its substrate.
Usnea filipendula – one of about 20,000 described species of lichen. The following outline provides an overview of and topical guide to lichens.. Lichen – composite organism made up of multiple species – a fungal partner, one or more photosynthetic partners, which can be either green algae or cyanobacteria, and, in at least 52 genera of lichens, a yeast. [1]
Edible lichens are lichens that have a cultural history of use as a food. Although almost all lichen are edible (with some notable poisonous exceptions like the wolf lichen , powdered sunshine lichen , and the ground lichen [ 1 ] ), not all have a cultural history of usage as an edible lichen.
The lichen's reproductive structures, or ascomata, are usually brightly coloured, and typically in the form of an apothecium – a wide, open, saucer-shaped or cup-shaped fruit body. In most species, these apotheciate ascomata have a lecanorine form, in which the apothecial disc is surrounded by a pale rim of tissue known as a thalline margin.