Family: Fabaceae

Origin, Description & Uses
Trifolium pratense (red clover) is a short-lived perennial legume native to Macaronesia, northwestern Africa, Europe, and temperate Asia, extending east to Mongolia and the Himalayas. It is recognized by its upright stems, three oval leaflets that often display a pale chevron, and rounded pink to reddish-purple flower heads that attract bees and other pollinators. Red clover has long been cultivated as a forage crop for livestock, a cover crop that improves soil fertility through nitrogen fixation, and as a nectar source for honey production. In Hawaiʻi, it has become naturalized in wet, open habitats including pastures and lawns at elevations of approximately 820–2,070 m on Maui and Hawaiʻi Island, where it was first collected on Hawaiʻi Island in 1932.

Risks & Threats
Red clover is naturalized in Hawaiʻi and possesses traits that are cause for concern, including prolific seed production, the ability to spread beyond cultivation, and nitrogen-fixing capabilities that can alter soil conditions. These characteristics may allow it to persist in disturbed habitats and potentially facilitate the establishment of other invasive species, posing a risk to tropical island ecosystems. Although it is primarily associated with pastures and other managed landscapes, it can spread into nearby open natural areas where suitable conditions exist. Because this species is already established in parts of Hawaiʻi, further planting should be avoided, particularly near natural areas or in regions where it is not yet widespread. When selecting forage, cover crops, or pollinator-friendly plants, choose a low-risk or native alternative whenever possible. In areas where red clover is already present, manage existing populations and prevent further spread to help minimize additional impacts on Hawaiʻi’s native ecosystems.

High Risk Traits:

• Broad climate suitability and elevation range exceeds 1000 m, demonstrating environmental versatility
  
• A temperate plant that can grow in subtropical climates
  
• Naturalized on Maui and Hawaii, Hawaiian Islands, and widely naturalized elsewhere
  
• A lawn and disturbance weed that may have adverse impacts on agriculture and the natural environment (but not considered a problem in the Hawaiian Islands)
  
• Other Trifolium species are invasive weeds
  
• Consumption by animals may cause problems in certain situations
  
• Shade-tolerant
  
• Tolerates many soil types (potential to invade not limited by substrate)
  
• Reproduces by seed and vegetatively by rooting at nodes
  
• A biennial, but may reach maturity in < 1 year in some areas
  
• Seeds dispersed internally and externally by animals, by water, and both accidentally and intentionally by people
  
• Seeds form a persistent seed bank. Some seeds may persist for 20-30+ years.
  
• May tolerate some mowing and grazing

Low Risk Traits:

• Despite naturalization and reports of weediness, generally not regarded as a problematic agricultural or environmental weed in the Hawaiian Islands
  
• Unarmed (no spines, thorns, or burrs)
  
• Provides fodder for livestock
  
• Mostly self-incompatible (although selfing has been documented in some cloned plants)
  
• Herbicides may provide effective control if removal is desired