SafePlants

Annual Ragweed (Ambrosia artemisiifolia)

Annual ragweed, scientifically known as Ambrosia artemisiifolia, is an annual broadleaved weed belonging to the composite or daisy family (Asteraceae). It is also commonly known as ambrosia, horseweed, asthma plant, fever weed, bitterweed, wild tansy, blackweed, Roman wormwood, and hogweed.

Considerations for Pets

• The plant's ragged appearance and hairy stems might be attractive to pets, potentially leading to ingestion.

Considerations for Children

• The plant's ragged appearance and hairy stems might be attractive to children, potentially leading to ingestion.

Taxonomy and Nomenclature

• Scientific Name: Ambrosia artemisiifolia L.
• Family: Asteraceae (also known as the sunflower or composite family)
• Synonyms:
  • Ambrosia artemisiifolia var. elatior
  • Ambrosia artemisiifolia var. paniculata
  • Ambrosia elatior
  • Ambrosia artemisiifolia var. elatior (L.) Desctils.
  • Ambrosia elatior

Distribution and Habitat

• Native to North America, particularly prevalent in eastern and north-central states.
• Introduced weed in various regions, including eastern Australia and Europe.
• Commonly found in disturbed sites, pastures, roadsides, wastelands, and poor or overgrazed pastures.

Ecological Role

• Considered a significant weed in Queensland and a declared pest under Queensland legislation.
• An invasive plant in Europe.
• Spreading rapidly in south-east Queensland.
• Can invade weak and overgrazed areas.

Morphological Characteristics and Growth Habits

• Erect annual herb, typically growing to 0.5-2 meters tall, but can reach up to 3.5 meters.
• Much-branched along a somewhat hairy stem.
• Shallow, fibrous root system.
• Leaves are grey-green, hairy, and variable. Lower leaves are ovate to lanceolate in outline, with a blade up to 16 cm long.