Coastal wattle vs Concentric Boulder Lichen

Acacia cyclops compared with Porpidia crustulata

Key Differences

Coastal wattle is Least Concern while Concentric Boulder Lichen is Vulnerable.

Taxonomic Classification

Rank	Coastal wattle	Concentric Boulder Lichen
Kingdom	Plantae (Plants)	Fungi (Fungi)
Phylum	Magnoliophyta (Flowering Plants)	Ascomycota (Sac Fungi)
Class	Magnoliopsida (Dicots)	Lecanoromycetes (Lecanoromycetes)
Order	Fabales (Legumes & Allies)	Lecideales (Lecideales)
Family	Fabaceae	Lecideaceae
Genus	Acacia	Porpidia
Species	Acacia cyclops	Porpidia crustulata

Conservation Status

Coastal wattle

LC — Least Concern

Concentric Boulder Lichen

VU — Vulnerable

Physical Characteristics

Attribute	Coastal wattle	Concentric Boulder Lichen
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Coastal wattle

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 8 distinct biome types spanning the Afrotropic and Palearctic realms. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Africa (13 countries), Asia (Israel), Europe (4 countries), and North America (United States).

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.

Coastal wattle

Coastal wattle (Acacia cyclops) is a dense, fast-growing shrub in the family Fabaceae, native to the southwestern and southern coastal regions of Western Australia, from Shark Bay south to the Nullarbor Plain. It grows on coastal dunes, sandy scrubland, and limestone substrates near the sea, where it tolerates salt spray, wind, and summer drought. Coastal wattle produces distinctive circular seeds with bright red arillate coatings, making them highly attractive to birds. Although valued in its native range for coastal stabilisation and revegetation, the species has become highly invasive in southern Africa, particularly South Africa, where it was introduced for dune stabilisation in the 19th century and has since spread extensively across the Cape Floristic Region, displacing native fynbos vegetation. It is listed among the 100 worst invasive species globally by the IUCN Invasive Species Specialist Group. In Australia, it is assessed as Least Concern. Management of invasive populations in South Africa involves mechanical removal and biological control efforts aimed at protecting the critically threatened fynbos biome.

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.