Family: Polygonaceae

Origin, Description & Uses
Rumex acetosella (field sorrel or sheep sorrel) is a low-growing perennial herb native to temperate regions of Eurasia. It typically forms spreading mats of slender stems and arrow-shaped leaves, often turning reddish with age. The plant produces small, reddish-green flower clusters and spreads readily through both seed and creeping rhizomes. Although sometimes used in traditional herbal remedies and as an edible sour green in small quantities, it is more commonly encountered as a pasture weed or volunteer species in disturbed landscapes.

Risks & Threats
In Hawaiʻi, Rumex acetosella is naturalized on Kauaʻi, Maui, and Hawaiʻi Island, where it occurs in disturbed mesic forests, subalpine woodlands, pastures, and along roadsides at elevations from about 1,115–2,840 m. This species is well adapted to acidic, nutrient-poor soils and can form dense groundcover that competes aggressively with native vegetation and pasture species. Its spreading rhizomes and abundant seed production allow it to persist and expand in open or disturbed habitats, where it may contribute to reduced native plant regeneration and altered ground layer communities. Because this species is naturalized and possesses traits that are cause for concern, it could detrimentally impact Hawaiʻi’s tropical island ecosystems. Choosing low-risk or native alternatives is recommended when available, and in areas where it is not yet widespread, limiting its use and actively managing existing populations can help reduce further spread and ecological impacts.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Broad climate suitability
  
• Naturalized in regions with subtropical climates
  
• Widely naturalized, including Kauai, Maui, and Hawaii
  
• Disturbance and crop weed
  
• Potential environmental weed
  
• Other Rumex species are invasive
  
• Potentially poisonous to livestock because of the presence of soluble oxalates
  
• Alternate host of crop diseases
  
• Mild allergen
  
• Tolerates many soil types
  
• May form dense stands that exclude other vegetation
  
• Reproduces by seeds and vegetatively from creeping roots and rhizomes
  
• Seeds dispersed by wind, water, mud, animals, vehicle tires, agricultural operations, and as contaminants in seed, grain, and hay
  
• Can form a persistent seed bank
  
• Tolerates mowing and cutting

Low Risk Traits:

• May threaten higher elevations of regions with tropical or subtropical climates
  
• Unarmed (no spines, thorns or burrs)
  
• Palatable to animals (despite potential toxicity)
  
• Possibly Shade-intolerant
  
• Primarily dioecious
  
• Herbicides may provide effective control