Lichenology

thumb|Lichen

thumb|Soredia on Evernia prunastri Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or green algae. These can be either scattered diffusely across the surface of the lichen's thallus, or produced in localized structures called soralia. Fungal hyphae make up the basic body structure of a lichen. The soredia are released through openings in the upper cortex of the lichen structure. After their release, the

thumb|right|Lichen grown in a Mickey Mouse shape thumb|right|13 years later thumb|right|17 years later In archaeology, palaeontology, and geomorphology, lichenometry is a geomorphic method of geochronologic dating that uses lichen growth to determine the age of exposed rock, based on a presumed specific rate of increase in radial size over time. Measuring the diameter of the largest lichen of a species on a rock surface can therefore be used to determine the length of time the rock has been exposed. Lichen can be preserved on old rock faces for up to 10,000 years, providing the maximum age lim

thumb|A herbarium specimen of the lichen [[Leptogium cyanescens, magnified 40X, with lobule-shaped isidia]]

form of lichen

thumb|Illustration showing cephalodium in relation to other parts of the lichen:1 – Cephalodium 2 – Cyanobacteria 3 – Cortex 4 – Green algal photobiont 5 – Medulla A cephalodium () is a small gall-like structure found in some lichens. They occur only in lichens which contain both cyanobacterial and green algal partners. Cephalodia can occur within the tissues of the lichen, or on its upper or lower surface. Lichens with cephalodia can fix nitrogen, and may be an important contributor of nitrogen to the ecosystem.

parasitic fungus that only lives on lichen

form of lichen

scientific journal