Family: Poaceae

Origin, Description & Uses
Cenchrus americanus, commonly known as bulrush millet or pearl millet, is a fast-growing annual grass native to tropical regions of Africa, from Benin to southern tropical Africa. It is widely cultivated in arid and semi-arid regions around the world as an important cereal crop for human consumption, livestock forage, hay, and cover cropping. The plant produces tall upright stems with narrow leaves and dense cylindrical flower spikes that resemble cattails. Pearl millet is valued for its drought tolerance, rapid growth, and ability to grow in poor soils where other grain crops may struggle.

Risks & Threats
In Hawaii, Cenchrus americanus has been reported as potentially naturalizing on Maui. This species possesses traits associated with invasive behavior, including rapid growth, prolific seed production, tolerance of dry and disturbed environments, and the ability to establish outside cultivation. As a naturalized high-risk species, it could detrimentally impact tropical island ecosystems by competing with native vegetation, altering habitat structure, and increasing fuel loads that may contribute to wildfire risk in dry habitats. Continued spread could threaten sensitive ecosystems and reduce native biodiversity. Because of these concerns, it is recommended that gardeners, landscapers, and agricultural producers choose low-risk or native alternatives whenever suitable options are available.

High Risk Traits:

• Naturalized
  
• Includes a large number of spontaneously occurring, weedy plants which mimic the crop in their vegetative and floral morphologies
  
• Thrives in tropical climates
  
• Grown between sea level and 1,800 m in the tropics (broad elevation range)
  
• May cause nitrate poisoning
  
• Possible host of pests and pathogens
  
• Tolerates many soil conditions (and potentially able to exploit many different habitat types)
  
• Self-compatible and wind-pollinated
  
• Annual (reproductive in <1 year)
  
• Seed contaminant
  
• Prolific seed production
  
• Tolerates cutting and grazing by animals

Low Risk Traits:

• Domesticated forms of this grass valuable for human use (grain and forage)
  
• Forage and fodder grass
  
• Not known to spread vegetatively
  
• Seeds predominantly gravity and human-dispersed
  
• Herbicides may provide effective control