Family: Poaceae

Origin, Description & Uses
Cenchrus americanus ‘Purple Majesty’ (ornamental pearl millet) is a cultivated ornamental variety of pearl millet originally derived from a species native to Africa and widely grown in tropical and subtropical regions around the world. This striking grass is prized for its tall upright form, deep purple foliage, and showy flower spikes that add bold color and texture to landscapes and container plantings. It is commonly used as a seasonal ornamental in gardens, borders, and mixed landscape designs because of its fast growth, drought tolerance, and dramatic appearance. Unlike agricultural pearl millet varieties, ‘Purple Majesty’ has primarily been selected for ornamental qualities rather than forage or grain production.

Risks & Threats
‘Purple Majesty’ is currently considered a Low Risk ornamental selection in Hawaii because it has not shown the same invasive tendencies associated with weedy forms of Cenchrus americanus (bulrush millet, pearl millet), which is considered High Risk in Hawaii. The ornamental cultivar is less commonly associated with naturalization and widespread establishment in natural areas. However, because it belongs to a species with known invasive potential, gardeners should still monitor for unwanted spread and avoid planting near sensitive ecosystems. Using sterile or carefully managed ornamental cultivars and preventing seed dispersal can help minimize any future risk to Hawaii’s native habitats.

High Risk Traits:

• The species Cenchrus americanus is High Risk
  
• Congeneric weeds exist
  
• Broad climate suitability (USDA Zones 8a–10b)
  
• Repeated introductions outside native range (ornamental)
  
• Produces viable seed
  
• Self-compatible (approx. 20% selfing)
  
• Annual life cycle (matures in 60–70 days)
  
• Intentionally dispersed by people (sold/traded)
  
• Potential seed contaminant for millet crops
  
• Prolific seed production (>1000/m²)
  
• Persistent seed bank (>1 year viability)

Low Risk Traits:

• Not naturalized beyond native range
  
• No spines, thorns, or burrs
  
• Not allelopathic or parasitic
  
• Not toxic to animals or humans
  
• Not shade-tolerant (requires full sun)
  
• Does not form dense thickets
  
• No vegetative spread
  
• No bird/animal dispersal (seeds cracked, unviable)
  
• Poor long-distance wind dispersal (reduced bracts/bristles)
  
• No water dispersal
  
• Low regeneration after fire or mutilation