vs Coastal Ragweed

Bacidia rosella compared with Ambrosia hispida

Key Differences

• is Critically Endangered while Coastal Ragweed is Least Concern.

Taxonomic Classification

Rank		Coastal Ragweed
Kingdom	Fungi (Fungi)	Plantae (Plants)
Phylum	Ascomycota (Sac Fungi)	Magnoliophyta (Flowering Plants)
Class	Lecanoromycetes (Lecanoromycetes)	Magnoliopsida (Dicots)
Order	Lecanorales (Lecanorales)	Asterales (Daisies & Sunflowers)
Family	Ramalinaceae	Asteraceae (Daisy Family)
Genus	Bacidia	Ambrosia
Species	Bacidia rosella	Ambrosia hispida

Conservation Status

CR — Critically Endangered

Coastal Ragweed

LC — Least Concern

Physical Characteristics

Attribute		Coastal Ragweed
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and boreal forests and taiga, among 5 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

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

Coastal Ragweed

Habitat

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

Range

Found in Cuba.

Bacidia rosella is a crustose lichen in the family Ramalinaceae, assessed as Critically Endangered (CR). It grows on the smooth bark of ancient trees in old-growth woodland habitats with long ecological continuity. Its critically endangered status reflects extreme rarity and the near-total loss of suitable veteran tree habitats across its range.

Coastal Ragweed

Coastal ragweed (Ambrosia hispida) is a perennial herb in the family Asteraceae, native to the coastal dunes, sandy beaches, and cays of Cuba, the Bahamas, and the wider Caribbean region. It grows in pioneer beach and dune vegetation, often forming spreading colonies that help stabilise loose coastal sands. Like other members of the genus Ambrosia, it bears inconspicuous greenish-white flowers arranged in racemes; male flower heads produce wind-dispersed pollen that can trigger allergic rhinitis in sensitive individuals. The deeply lobed, hispid leaves are adapted to reflect intense solar radiation and tolerate salt spray. Coastal ragweed plays an ecological role in early dune succession, binding sand and enabling other plant species to establish. The genus is widespread globally, with several Ambrosia species considered noxious weeds in agricultural settings, though Ambrosia hispida is restricted to its native Caribbean coastal range. The IUCN assesses it as Least Concern, reflecting adequate population size across its Caribbean coastal distribution. Pressure from coastal development and tourism infrastructure poses a localised threat to dune communities it inhabits.