Family: Cyperaceae

Origin, Description & Uses
Schoenoplectus californicus (California bulrush, giant bulrush) is a tall, perennial wetland sedge native to a broad range extending from the southern United States through Central and South America, as well as Easter Island. It grows in marshes, ponds, stream margins, and other freshwater wetlands, forming dense stands of upright, leafless green stems that can reach several meters in height. The species has long been valued for traditional uses, including weaving mats, baskets, and other handicrafts, and is also planted for wetland restoration, erosion control, wildlife habitat enhancement, and ornamental water gardens.

Risks & Threats
California bulrush is naturalized on Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi Island. This species possesses traits that are cause for concern, including rapid vegetative spread through rhizomes, prolific growth in wet habitats, and the ability to form dense monocultures that displace native wetland vegetation. These characteristics allow it to alter habitat structure, reduce plant diversity, and potentially impact native species dependent on open or diverse wetland ecosystems. Because it is already widespread in Hawaiʻi, management efforts should focus on preventing its introduction and spread into wetlands and watersheds where it is not yet well established. When selecting plants for restoration, landscaping, or aquatic habitats, choosing low-risk or native alternatives is recommended whenever suitable options are available to help protect Hawaiʻi’s unique tropical island ecosystems from further ecological impacts.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Able to grow in tropical climates
  
• Naturalized (or possibly native) in the Hawaiian Islands, and New Zealand
  
• Regarded as an environmental weed
  
• Other Schoenoplectus species are invasive
  
• Possibly allelopathic
  
• Tolerates many soil types
  
• Forms dense thickets in native and introduced ranges
  
• Reproduces by seeds and vegetatively by rhizomes
  
• Seeds and vegetative fragments dispersed by water
  
• In addition to water, seeds may be dispersed by wind, contaminated soil and feed, machinery, and wildlife

Low Risk Traits:

• Where native, an important component of wetland habitat
  
• Unarmed (no spines, thorns or burrs)
  
• Seed production may be limited and may limit dispersal potential
  
• Non-toxic and palatable to animals and humans
  
• Herbicides may provide effective control