Family: Poaceae

Origin, Description & Uses
Echinochloa crus-galli subsp. utilis, commonly known as Japanese millet (synonym: Echinochloa esculenta), is an annual grass domesticated in East Asia and grown as a cereal and forage crop. It is a cultivated form of barnyard grass, originally selected for larger seeds and improved grain production. This fast-growing grass can reach several feet in height and produces dense, bristly seed heads. Japanese millet is used as a grain for human consumption, livestock feed, cover cropping, and wildlife forage. It grows quickly in warm weather and tolerates a range of soil conditions, including wet or seasonally flooded areas.

Risks & Threats
Japanese millet is currently potentially naturalizing on Maui, and it possesses traits that are cause for concern. As a close relative of barnyard grass—a widespread and aggressive weed—it grows rapidly, produces abundant seed, and can thrive in disturbed, agricultural, and wetland habitats. These characteristics increase the risk that it could spread further across Hawaiian islands, competing with native plants, altering wetland ecosystems, and affecting agriculture. Plant Pono recommends choosing a low-risk or native alternative to help protect Hawaii’s unique ecosystems.

High Risk Traits:

• Widely naturalized beyond native range
  
• Closely related to major agricultural weeds (E. crus-galli, E. colona)
  
• Tolerates wide range of soils (including salinity and waterlogging)
  
• Annual plant with rapid lifecycle (60 days to flower)
  
• Can hybridize with weedy relatives
  
• Self-compatible (can reproduce solo)
  
• Numerous dispersal methods: cultivated intentionally, contaminant in grain, spread by water and animals

Low Risk Traits:

• No evidence of being a severe agricultural or environmental weed
  
• Palatable to livestock (grown for forage)
  
• No spines, shade intolerant, non-parasitic
  
• Generally non-toxic (one suspected toxicity case noted)
  
• Susceptible to common herbicides