Family: Asteraceae

Origin, Description & Uses
Black-eyed Susan (Rudbeckia hirta) is a short-lived perennial or biennial wildflower native to central and eastern Canada and the United States. It is well known for its bright, daisy-like yellow petals surrounding a dark brown central cone. The plant typically grows in sunny, open habitats such as prairies, meadows, and roadsides, and is widely cultivated as an ornamental flower in gardens. It is also valued for its role in pollinator plantings, providing nectar and pollen for bees, butterflies, and other beneficial insects, and is sometimes used in native-style landscaping and cut flower arrangements.

Risks & Threats
Although Rudbeckia hirta is not currently known to be naturalized in the Hawaiian Islands, it does possess traits that are cause for concern. It produces abundant seed, establishes readily in disturbed soils, and is highly adaptable to a range of environmental conditions, which could allow it to spread beyond intended plantings in tropical island ecosystems. If it were to become established, it could potentially compete with native vegetation in open or disturbed habitats and contribute to changes in plant community structure. For these reasons, caution is advised in its use, and choosing a low-risk or native alternative is recommended when suitable options are available.

High Risk Traits:

• Elevation range exceeds 1000 m
  
• Widely naturalized
  
• A garden weed
  
• Related Rudbeckia species have become invasive
  
• Toxic to cattle and other animals
  
• Sap can cause dermatitis and may be poisonous if ingested
  
• Tolerates many soil types
  
• Able to reach maturity in as little as one year
  
• Seeds dispersed accidentally and intentionally by people and as a seed contaminant
  
• Forms a persistent seed bank
  
• Can resprout from the root crown

Low Risk Traits:

• Grows in temperate climates (may only threaten higher elevations in tropical ecosystems)
  
• Browsed by animals
  
• Ornamental
  
• Self-incompatible