Family: Juncaceae

Origin, Description & Uses:
Luzula sylvatica (greater woodrush) is a perennial plant native to Europe extending into the Caucasus region, where it typically grows in cool, moist, temperate woodland environments. It forms dense, evergreen clumps of grass-like foliage and is often used as an ornamental groundcover in shaded garden settings. Because of its tolerance for low light and ability to thrive in damp soils, it is sometimes planted for erosion control and to provide year-round greenery in woodland-style landscapes.

Risks & Threats:
Although Luzula sylvatica is currently not known to be naturalized in the Hawaiian Islands, it does possess traits that are cause for concern, including shade tolerance, vigorous groundcover growth, and the ability to spread in moist forest environments. In other regions, similar characteristics have allowed it to form dense patches that can outcompete native understory vegetation and alter natural forest floor dynamics. If introduced to suitable habitats in Hawaiʻi—particularly wet, shaded upland forests—it could potentially spread and negatively affect native plant communities. Because of these risks, it is recommended to choose a low-risk or Hawaiian native alternative when suitable options are available.

High Risk Traits:

• Grown as an ornamental outside native range
  
• Listed on prohibited species list in Australia
  
• Congeneric (L. luzuloides) is an environmental weed
  
• Shade tolerant
  
• Forms dense, weed-proof mats/tussocks
  
• Produces viable seed
  
• Reproduces by rhizomes (vegetative fragmentation)
  
• Propagules dispersed intentionally by people
  
• Propagules dispersed as a produce contaminant
  
• Seeds dispersed by water
  
• Prolific seed production (~700 seeds/gram)
  
• Possible persistent seed bank (based on congener)

Low Risk Traits:

• Native to temperate regions, not tropical/subtropical
  
• Not naturalized beyond native range (score suggests no)
  
• No spines, thorns, or burrs
  
• Not allelopathic or parasitic
  
• Palatable to grazing animals
  
• Not toxic to animals
  
• Does not create fire hazard
  
• Poor tolerance to soil moisture changes (needs high humidity)
  
• Slow growth/reproduction rate (2+ years to mature)
  
• Intolerant of disturbance (clearcutting, heavy traffic)