SafePlants

River Jelly Lichen (Collema dichotomum)

The River Jelly Lichen, scientifically known as Collema dichotomum, is a fascinating example of a lichen that thrives in aquatic environments. Its unique jelly-like texture and seaweed-like appearance distinguish it from other lichens.

Considerations for Pets

• Jelly lichens, in general, become jelly-like when wet, absorbing water.

Considerations for Children

• Jelly lichens, in general, become jelly-like when wet, absorbing water.

Taxonomy and Nomenclature

• Scientific Name: Collema dichotomum (With.) Coppins &amp Laundon
• Common Name: River Jelly Lichen
• Family: Collemataceae
• Order: Lecanorales
• Synonyms: Some texts mention other Collema species like Collema ohioense which might have been previously misidentified or considered variations.

Description and Morphology

• The thallus (lichen body) is foliose (leafy), black, and gelatinous when wet.
• It can grow up to 2-4 cm broad.
• The lobes are broadly rounded.
• Isidia and soredia are lacking.
• Spores are 4-septate, hyaline, and measure 20-40 by 3-4.5 µm.
• Other Collema species have finger-like lobes that are 1-2 cm long and convex.
• Its growth habits are lichenous.

Distribution and Habitat

• The River Jelly Lichen is an aquatic lichen.
• It grows on submerged rocks and boulders in fast-flowing rivers.
• It has been found in the upper reaches of rivers, including those in Northumberland.
• It has also been identified in Wales, where there is a specific action plan for its conservation.

Ecological Role

• The River Jelly Lichen is recognized as a key species in certain ecosystems, particularly in the context of river health.
• Conservation efforts are focused on safeguarding it from developments that might compromise its habitat, such as outdoor river pursuits.

Interactions with Other Organisms

• The photobiont (the photosynthetic partner in the lichen symbiosis) is the cyanobacterium genus Nostoc.

Quirky Facts

• Collema dichotomum is described as looking more like seaweed than a typical lichen.
• Some texts indicate that in the game context, this lichen is able to be battled.
• Another jelly lichen is named 'bat's wings' because when it rains it absorbs water until it is jelly-like.

Further Information

• ARKive (mentioned for photos and facts)
• Encyclopedia of Life
• Partnership with Nature: A Local Biodiversity Action Plan for Wales (September 2002)
• NBNSYS0000018437 (Taxon Version Key)
• Australian Plant Names Index