Blue star vs Concentric Boulder Lichen

Amsonia orientalis compared with Porpidia crustulata

Key Differences

• Blue star is Critically Endangered while Concentric Boulder Lichen is Vulnerable.

Taxonomic Classification

Rank	Blue star	Concentric Boulder Lichen
Kingdom	Plantae (Pflanzen)	Fungi (Pilze)
Phylum	Magnoliophyta (Flowering Plants)	Ascomycota (Schlauchpilze)
Class	Magnoliopsida (Dicots)	Lecanoromycetes (Lecanoromycetes)
Order	Gentianales (Enzianartige)	Lecideales (Lecideales)
Family	Apocynaceae	Lecideaceae
Genus	Amsonia	Porpidia
Species	Amsonia orientalis	Porpidia crustulata

Conservation Status

Blue star

CR — Critically Endangered

Concentric Boulder Lichen

VU — Vulnerable

Physical Characteristics

Attribute	Blue star	Concentric Boulder Lichen
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Blue star

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Concentric Boulder Lichen

Habitat

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

Range

Distributed across Denmark, Norway, Portugal, Sweden, and United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Blue star

The Blue star (Amsonia orientalis) is a species in the genus Amsonia. It is currently classified as Critically Endangered on the IUCN Red List. Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Concentric Boulder Lichen

<em>Porpidia crustulata</em>, commonly known as the Concentric Boulder Lichen, is a crustose lichen in the family Porpidiaceae formed through a symbiotic relationship between a fungal partner (mycobiont) and photosynthetic green algae (photobiont). Like all crustose lichens, it grows tightly appressed to its substrate—typically siliceous or acidic rock surfaces including boulders, cliff faces, and pebbles in open, well-lit habitats—forming thin, grayish to pale thalli marked by scattered black apothecia (reproductive discs). <em>Porpidia crustulata</em> derives nutrition entirely through photosynthesis conducted by its algal partner, requiring no external organic food source. The species has been documented in Denmark, Norway, Portugal, Sweden, and the United States, suggesting a broad boreal to temperate distribution across the Northern Hemisphere. It is currently classified as Vulnerable by the IUCN, indicating significant conservation concern, likely linked to threats including air pollution, acidification, quarrying of rocky habitats, and changes in land use that reduce the availability of suitable substrates. Crustose lichens are typically slow-growing, long-lived organisms with limited capacity for rapid range shifts in response to environmental change. Biological traits such as individual lifespan, growth rates, and reproductive output remain poorly documented at the population level.