SafePlants

River Jelly Lichen (Collema dichotomum)

The River Jelly Lichen, scientifically known as Collema dichotomum, is a fascinating lichen species that resembles seaweed more than a typical plant. It gets its common name from its jelly-like texture when wet and its frequent habitat near rivers.

Considerations for Pets

• This lichen has a jelly-like texture when wet, which could be appealing to pets.
• It often grows on rocks and boulders, which might be areas pets explore.

Considerations for Children

• This lichen has a jelly-like texture when wet, which could be appealing to children.
• It often grows on rocks and boulders, which might be areas children explore.

Taxonomy and Nomenclature

• Scientific Name: Collema dichotomum (With.) Coppins & Laundon
• Common Name: River Jelly Lichen
• Family: Collemataceae
• Order: Lecanorales
• Synonyms: C. ohioense (for Collema Conglomeratum)

Distribution and Habitat

• The River Jelly Lichen grows on submerged rocks and boulders in fast-flowing rivers.
• It has been found in Northumberland, UK, and is associated with the River Exe project.

Morphological Characteristics

• The thallus (lichen body) is foliose (leafy), black, and gelatinous when wet.
• It forms broadly rounded lobes.
• Spores are 4-septate (divided into four parts), hyaline (translucent), and measure 20-40 by 3-4.5.

Quirky Facts

• When it rains, this lichen absorbs water until it is jelly-like.
• The River Jelly Lichen is sometimes mistaken for seaweed.

Ecological Role

• It's important to ensure canoe access and other river activities do not adversely affect populations of river jelly lichen.
• Safeguarding against developments such as outdoor river pursuits that might compromise the conservation of the lichen is essential.

Interactions with Other Organisms

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

Further Information

• Encyclopedia of Life
• ARKive
• Australian Plant Names Index