Chalk Screw-moss vs Coastal Ragweed

Tortula vahliana compared with Ambrosia hispida

Key Differences

• Chalk Screw-moss is Vulnerable while Coastal Ragweed is Least Concern.

Taxonomic Classification

Rank	Chalk Screw-moss	Coastal Ragweed
Kingdom same	Plantae (Plants)	Plantae (Plants)
Phylum	Bryophyta	Magnoliophyta (Flowering Plants)
Class	Bryopsida (Bryopsida)	Magnoliopsida (Dicots)
Order	Pottiales (Pottiales)	Asterales (Daisies & Sunflowers)
Family	Pottiaceae	Asteraceae (Daisy Family)
Genus	Tortula	Ambrosia
Species	Tortula vahliana	Ambrosia hispida

Evolutionary Relationship

Chalk Screw-moss and Coastal Ragweed share a common ancestor at the Kingdom level: Plantae. (Plants)

Conservation Status

Chalk Screw-moss

VU — Vulnerable

Coastal Ragweed

LC — Least Concern

Physical Characteristics

Attribute	Chalk Screw-moss	Coastal Ragweed
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Chalk Screw-moss

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Belgium, Norway, and Portugal. Currently classified as Vulnerable 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.

Chalk Screw-moss

The Chalk Screw-moss (Tortula vahliana) is a species in the genus Tortula. It is currently classified as Vulnerable on the IUCN Red List. Native to Europe, inhabiting ecosystems characteristic of the region.

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.