Brook Floater vs Cliff Scalewort

Alasmidonta varicosa compared with Porella cordaeana

Key Differences

Brook Floater is Vulnerable while Cliff Scalewort is Least Concern.

Taxonomic Classification

Rank	Brook Floater	Cliff Scalewort
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Mollusca (Mollusks)	Marchantiophyta (liverwort)
Class	Bivalvia (Bivalvia)	Jungermanniopsida (Jungermanniopsida)
Order	Unionida (Unionida)	Porellales (Porellales)
Family	Unionidae	Porellaceae
Genus	Alasmidonta	Porella
Species	Alasmidonta varicosa	Porella cordaeana

Conservation Status

Brook Floater

VU — Vulnerable

Cliff Scalewort

LC — Least Concern

Physical Characteristics

Attribute	Brook Floater	Cliff Scalewort
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brook Floater

Habitat

Native to North America, inhabiting ecosystems characteristic of the region.

Range

Found in United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Cliff Scalewort

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Found across Europe (6 countries) and North America (United States).

Brook Floater

The Brook Floater (Alasmidonta varicosa) is a species in the genus Alasmidonta. It is currently classified as Vulnerable on the IUCN Red List. Native to North America, inhabiting ecosystems characteristic of the region.

Cliff Scalewort

Cliff Scalewort, Porella obtusata, is a leafy liverwort in the family Porellaceae found on cliff faces, shaded rock surfaces, and the bark of trees in moist, humid environments across Europe and North America. Porella is one of the most diverse and widely distributed leafy liverwort genera, with species adapted to a range of substrates from bark and rock to soil in forests and coastal habitats. Cliff Scalewort forms flat, overlapping mats of small, scale-like leaves arranged in two lateral rows and a row of smaller underleaves, creating a texture that gives the plant its common name. The green to brownish-green plants are tightly appressed to the surface, extracting moisture from rainfall and condensation. Liverworts in this family reproduce sexually when conditions are favorable, producing small capsules on delicate setae, as well as vegetatively through fragmentation. Porella species on cliff faces are sensitive to air pollution, particularly sulfur dioxide, and have declined in many industrial regions of Europe, recovering more recently as air quality has improved. They serve as indicators of habitat continuity and air quality in ecological assessments. Cliff Scalewort is not globally threatened but may be locally rare in heavily polluted or drought-prone areas.