Family: Poaceae

Origin, Description & Uses
Urochloa ramosa, commonly known as browntop millet or Dixie signalgrass, is an annual grass native to tropical Asia and Africa. It has been widely introduced to warm regions of the world, including the southern United States, where it has been cultivated since the early 20th century. This adaptable grass grows quickly in a variety of soil types and climates, making it useful as a forage crop for livestock and, in some areas, for erosion control and cover cropping. While it can provide nutritious forage, it may accumulate toxic levels of nitrate when stressed by drought or cold weather, making careful livestock management important.

Risks & Threats
Urochloa ramosa is considered a high-risk species for Hawaiʻi. It is potentially naturalizing on Oʻahu and possesses traits associated with invasive grasses, including rapid growth, abundant seed production, and the ability to establish in disturbed habitats. These characteristics increase its potential to spread beyond cultivation, compete with native vegetation, and alter tropical island ecosystems. Because of these risks, Plant Pono recommends choosing a low-risk or native alternative whenever suitable options are available. Preventing additional plantings and limiting its use in areas where it is not yet established can help reduce the risk of further spread and minimize future impacts on Hawaiʻi’s natural and agricultural landscapes

High Risk Traits:

• Broad climate suitability
  
• Grows and able to spread in tropical regions
  
• Naturalized in Australia and North America (Mexico and SE USA), potentially naturalizing on Oʻahu
  
• A weedy grass and minor agricultural weed reported to impact quality and yield of certain crops
  
• Other Urochloa species are invasive weeds
  
• Can accumulate toxic levels of nitrate and should not be fed to livestock if the grass has been stressed by drought or cold conditions
  
• Tolerates many soil types
  
• Reproduces by seeds
  
• Annual/perennial life cycle (able to reach maturity in one growing season)
  
• Seeds dispersed by cultivation, possibly water, and potentially by animals or as a crop contaminant
  
• Seeds may form a persistent seed bank

Low Risk Traits:

• A domesticated crop with cultivated forms that have greatly reduced dispersibility
  
• Weedy impacts appear to be restricted to certain crops
  
• Unarmed (no spines, thorns, or burrs)
  
• Valued pasture grass and source of feed for birds
  
• Grows best in high light environments (dense shade may inhibit spread)
  
• Herbicides, mowing and potentially fire may provide effective control