Family: Cyperaceae

Origin, Description & Uses:
Eleocharis geniculata, commonly known as bent spikerush, Canada spikesedge, or spikerush, is a small wetland sedge that occurs naturally in tropical and subtropical regions around the world. It grows in moist soils, shallow water, and along the edges of ponds, wetlands, ditches, and other seasonally flooded areas. This grass-like plant forms clumps of slender, upright to slightly bent green stems topped with small spike-like flower heads. Because it tolerates wet conditions and fluctuating water levels, it has sometimes been used in wetland plantings, erosion control, and habitat restoration projects. Like other sedges, it can also provide limited forage and habitat for wildlife in wetland environments.

Risks & Threats:
In Hawaiʻi, Eleocharis geniculata is naturalized on Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and Hawaiʻi Island. The species produces abundant seeds and can spread readily in muddy or seasonally flooded habitats. Its ability to establish quickly in disturbed wetlands and along waterways allows it to form dense stands that may compete with native wetland plants. These traits are cause for concern because aggressive wetland species can alter habitat structure and reduce biodiversity in sensitive tropical island ecosystems. Because it is already naturalized and has the potential to spread further, planting this species is not recommended. Instead, consider choosing a low-risk or native wetland plant species better suited for Hawaiʻi’s ecosystems.

High Risk Traits:

• Broad elevation range and climate suitability
  
• Grows in temperate to tropical climates
  
• Naturalized on Kauai, Oahu, Molokai, Maui, and Lanai (Hawaiian Islands)
  
• A weed of rice crops
  
• Other Eleocharis species have become invasive
  
• Potentially allelopathic
  
• Grows in full sun to shade
  
• Tolerates many soil types
  
• Capable of forming dense stands
  
• Reproduces by seeds
  
• Annual
  
• Seeds dispersed by water, and possibly by adhering to birds, other animals, and people
  
• Forms a persistent seed bank

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Palatable to animals
  
• Non-toxic
  
• Non-rhizomatous, not reported to spread vegetatively