SafePlants

River Jelly Lichen: A Fascinating Symbiosis

Considerations for Pets

• This lichen is aquatic, growing on submerged rocks. Its presence in aquariums or outdoor water features might warrant observation to ensure it doesn't pose any unforeseen risks.

The River Jelly Lichen, scientifically known as Collema dichotomum, is a unique and intriguing organism. Its common name aptly describes its gelatinous texture when wet and its preference for aquatic environments.

Taxonomy and Nomenclature

• Scientific Name: Collema dichotomum (With.) Coppins &amp Laundon
• Common Name: River Jelly Lichen
• Family: Collemataceae
• Order: Lecanorales
• Synonyms: While not explicitly stated, the mention of "Collema (jelly lichen)" suggests that other species within the Collema genus could be considered related.
• Taxon Version Key: NBNSYS0000018437

Description

• The thallus (lichen body) is foliose, black, and gelatinous when wet.
• It features broadly rounded lobes.
• Isidia and soredia are lacking.
• Spores are 4-septate, hyaline, and measure 20-40 by 3-4.5.

Distribution and Habitat

• This aquatic lichen grows on submerged rocks and boulders in fast-flowing rivers.
• It is found in the upper reaches of rivers, including those in Northumberland, UK.

Ecological Role

• It's a key species, and its populations should be safeguarded against developments that might compromise its conservation.
• Canoe access should be managed to avoid adverse effects on river jelly lichen populations.

Interactions with Other Organisms

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

Quirky Facts

• Collema dichotomum "looks more like a seaweed than a lichen".
• When it rains jelly lichens absorb water until it is jelly-like.

Further Information

• Learn more at ARKive (now offline).
• Encyclopedia of Life.