Family: Poaceae

Origin, Description & Uses:
Zoysia matrella, commonly known as Manila grass, is a warm-season turfgrass native to tropical and subtropical Asia and parts of the northwestern Pacific. It forms a dense, fine-textured lawn with narrow leaves and spreads by creeping stolons and rhizomes, creating a durable, carpet-like cover. Because of its tolerance for heat, salt spray, drought, and moderate foot traffic, it is widely planted for residential lawns, golf courses, parks, resorts, and other landscaped areas in warm climates.

Risks & Threats:
In Hawaiʻi, Zoysia matrella is naturalized on Kauaʻi and Oʻahu and is potentially naturalizing on Lānaʻi. This species possesses traits that are cause for concern, including vigorous vegetative spread and the ability to persist beyond cultivated landscapes. Dense mats of grass can suppress other vegetation and may detrimentally impact tropical island ecosystems by reducing native plant establishment and altering ground-layer habitats. Because it is already established in parts of the state, planting should be avoided in or near natural areas, and existing populations should be managed to prevent further spread into places where it is not yet widespread. When suitable, choose a low-risk or native groundcover or turf alternative to help protect Hawaiʻi’s unique ecosystems.

High Risk Traits:

• Able to grow in regions with tropical climates
  
• Kaua'i Naturalized; O'ahu Naturalized; Lana'i Potentially naturalizing
  
• Reported as a weed of rice and other crops in Asia (impacts unspecified)
  
• Pollen may be an allergen to susceptible individuals
  
• Shade-tolerant
  
• Tolerates many soil types
  
• Forms dense cover that can choke out other vegetation
  
• Reproduces by seeds (some cultivars may be sterile) and vegetatively by rhizomes
  
• Hybridizes with Zoysia sinica
  
• Self-compatible
  
• Grazing animals may disperse seeds; intentionally cultivated as a turf grass
  
• Tolerates mowing and grazing

Low Risk Traits:

• Despite reports of weediness, no detrimental impacts have been quantified.
  
• Unarmed (no spines, thorns, or burrs)
  
• Provides forage for grazing animals
  
• Valued lawn grass
  
• Propagated vegetatively. Seed production in cultivation may be limited, and minimize risk of long-distance dispersal (esp. for some cultivars)