Family: Asteraceae

Cyanthillium cinereum, commonly known as little ironweed, is a flowering plant in the Asteraceae family. It is native to tropical and subtropical regions of Asia, Africa, and Australia. The plant is an annual herb that grows over 1 meter tall, with slender stems, lance-shaped leaves, and small purple or pinkish flower heads. It thrives in disturbed habitats, such as roadsides, agricultural fields, and wastelands, and is often considered a weed.

Cyanthillium cinereum is known for its adaptability and ability to colonize disturbed areas quickly. While it is not typically classified as a highly invasive species, it can become problematic in certain regions due to its aggressive growth and competition with native vegetation. It can spread by wind-dispersed seeds, as a crop or soil contaminant, and is naturalized on all the main Hawaiian Islands. It has been identified as one of several weed threats in the cliff habitat of Schiedea spergulina var. leiopoda, an endangered species from the island of Kauai.

High Risk Traits:

• Broad climate suitability
  
• Thrives and can spread in regions with tropical climates
  
• Widely naturalized, including all the main Hawaiian Islands
  
• A disturbance, crop and potential environmental weed
  
• Host of the tobacco leaf curl virus and the root-knot nematode
  
• Tolerates many soil types (not limited by substrate)
  
• Can form dense cover in disturbed habitats
  
• Reproduces by seed
  
• Capable of self-fertilization
  
• Reaches maturity in 1 growing season
  
• Seeds dispersed by wind and as a contaminant in crop seeds, pasture seeds and in agricultural machinery
  
• Reported to tolerate, or benefit from, cultivation, browsing pressure, mutilation, fire etc.

Low Risk Traits:

• Although widely naturalized and reported to be a crop and possible environmental weed, direct impacts from this plant have rarely been documented
  
• Unarmed (no spines, thorns, or burrs)
  
• Palatable to animals
  
• Not reported to be toxic
  
• Grows best in high light environments (dense shade may inhibit spread)
  
• Seeds lack dormancy and germinate rapidly (unlikely to form a persistent seed bank)