Thallus
Definition
The body of a lichen, consisting of fungal hyphae housing algal or cyanobacterial cells. The thallus diameter or area is the measurement used in lichenometry.
- Composition
- Fungal hyphae housing algal or cyanobacterial cells
- Growth forms
- Crustose, foliose, or fruticose
- Measured as
- Diameter or area
- Used for
- Lichenometric dating of exposed surfaces
Common questions
How does thallus size estimate time since exposure?+
Growth rate curves calibrated for the species and region convert measured diameter into an elapsed-time estimate, though rates vary with substrate, aspect, and moisture and need local calibration.
Why is lichenometry limited in forensic PMI use?+
Growth rates are slow and site specific, calibration curves are often missing for a given locality, and the method mainly applies to exposed stone or bone surfaces over long timescales, not fresh remains.
Related terms
- Biological Soil Crust (Biocrust)
- A community of cyanobacteria, algae, mosses, fungi, and lichens that colonises bare soil surfaces and forms a thin coherent mat. Relevant to...
- Crustose Lichen
- A lichen growth form in which the thallus grows flat against and into the substrate (bone, stone, wood) and cannot be removed...
- Epilithic / Epixylous Colonisation
- Growth of organisms on rock or stone surfaces (epilithic) or on dead wood (epixylous). In forensic contexts, colonisation of bone surfaces by...
- Lichenometry
- The use of lichen thallus diameter to estimate the minimum age of a surface. Based on the known or measured radial growth...
- Succession
- The predictable sequence of different insect species colonising remains as decomposition progresses. Early stages attract blow flies; later stages attract beetles, moths,...