LICHENS

• Lichens have a composite thalloid nature (composed of two different organisms: algae and fungi)
• Lichens can potentially grown any surface (especially rocks) or as an epiphyte
• Lichens reproduce asexually by fragmentation; some release soredia (special dispersal units) that contains cells of both partners
• The symbiotic mutual relationship between algae and fungi provides each other benefits; fungi absorbs nutrients from the source while algae and produce food via photosynthesis
• Lichen grows slowly and may live for centuries in extreme temperature and moisture
• They have been used in foods and to extracts chemicals as dyes or antimicrobial substances
• Some are very sensitive to pollution (vacuoles cannot store or sequester absorbed elements), especially with sulfur dioxide, and have been used as environmental indicators
• Lichens have a body called thallus

  • cortex – outer, tightly packed fungal layer
  • medulla – inner loosely packed fungal layer
  • rhizines – hyphal bundles attached to the substrate
• GENERAL GROWTH FORMS OF LICHENS

  CRUSTOSE - Flat lichens that grow tightly attached to a rock or any surface they were growing
• GENERAL GROWTH FORMS OF LICHENS

  FOLIOSE - Flat lichens that have leaf-like lobes and are not attached tightly
• GENERAL GROWTH FORMS OF LICHENS

  FRUTICOSE - Lichens that grows erectly and are branched and shrub-like