SafePlants

Rim Lichens: A Colorful World of Symbiosis

Lichens, often overlooked, are fascinating symbiotic organisms, not single plants. They are composed of fungi, algae, and sometimes bacteria, living together in a mutually beneficial relationship.

Considerations for Pets

• Lichens come in many shapes, sizes, and colors.
• Some lichens have apothecia, which are small, rimmed cups or disks on the surface.

Considerations for Children

• Lichens come in many shapes, sizes, and colors.
• Some lichens have apothecia, which are small, rimmed cups or disks on the surface.

Common Names

• Rim Lichen

Taxonomy and Nomenclature

• Lichens are not classified within the traditional plant or animal kingdoms. Instead, they are symbiotic organisms resulting from the association between fungi and algae (or cyanobacteria).
• Examples mentioned include:
  • Aspicilia calcarea (calcareous rimmed lichen)
  • Aspicilia reptans (Rimmed Lichen)
  • Peltigera polydactylon (Many-fruited pelt lichen)
  • Pannaria conoplea (Mealy-rimmed shingle lichen)
  • Caloplaca cerina (Gray-rimmed firedot lichen)
  • Ochrolechia oregonensis ("Double-rim saucer lichen")

Distribution and Habitat

• Lichens are found in diverse environments, from woodlands to rocky outcrops and even concrete surfaces.
• Specific locations mentioned include:
  • Rocky Mountains
  • Oregon Coast Range
  • Singapore (Bukit area)
  • Southeast Alaska
  • Southern Ohio
  • New Mexico

Morphological Characteristics and Growth Habits

• Lichens exhibit various growth forms, including:
  • Foliose (leaf-like)
  • Fruticose (shrub-like)
  • Crustose (crust-like)
• Many lichens develop a rim (thalline rim or exciple) around their thallus (body), which can be the same color as the thallus or a contrasting color.
• Apothecia (fruiting bodies) are often present as small, rimmed cups or disks.
• Color can vary greatly and is an important identification characteristic.

Ecological Role

• Lichens are early colonizers of bare substrates like soil, rock, and peat.
• They can be sensitive to air pollution, making them useful bioindicators.
• Some moths mimic the colors of lichens, providing them with camouflage.

Interactions with Other Organisms

• Lichens form symbiotic relationships with algae and/or cyanobacteria.
• Parasitic fungi can grow on lichens.
• Moths can exhibit lichen mimicry for camouflage.

Quirky Facts

• "Surprise lichen" (Bacidia schweinitzii) is noted for strikingly contrasting colors that become apparent under certain conditions.