Arctic grass vs Concentric Boulder Lichen

Arctagrostis latifolia compared with Porpidia crustulata

Key Differences

Arctic grass is Near Threatened while Concentric Boulder Lichen is Vulnerable.

Taxonomic Classification

Rank	Arctic grass	Concentric Boulder Lichen
Kingdom	Plantae (Plants)	Fungi (Fungi)
Phylum	Magnoliophyta (Flowering Plants)	Ascomycota (Sac Fungi)
Class	Liliopsida (Monocots)	Lecanoromycetes (Lecanoromycetes)
Order	Poales (Grasses)	Lecideales (Lecideales)
Family	Poaceae (Grass Family)	Lecideaceae
Genus	Arctagrostis	Porpidia
Species	Arctagrostis latifolia	Porpidia crustulata

Conservation Status

Arctic grass

NT — Near Threatened

Concentric Boulder Lichen

VU — Vulnerable

Physical Characteristics

Attribute	Arctic grass	Concentric Boulder Lichen
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Arctic grass

Habitat

Typically found in grasslands, wetlands, forests, and cultivated landscapes.

Range

Distributed across Norway and Sweden. Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

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.

Arctic grass

The Arctic grass (Arctagrostis latifolia) is a species in the genus Arctagrostis. It is currently classified as Near Threatened on the IUCN Red List. Typically found in grasslands, wetlands, forests, and cultivated landscapes.

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.