Family: Poaceae
Origin, Description & Uses
Themeda villosa, commonly known as greater tasselgrass, Lyon’s grass, or silky kangaroo grass, is a perennial bunchgrass native to tropical and subtropical regions of Asia. It forms dense clumps of narrow leaves topped with distinctive silky, feathery flower heads that give the grass an ornamental appearance. The species has been used as a pasture grass for livestock, for erosion control on disturbed slopes, and occasionally as an ornamental grass in naturalistic landscapes due to its attractive seed heads and tolerance of warm climates.
Risks & Threats
Themeda villosa is naturalized in Hawaiʻi and is known from Kauaʻi, Oʻahu, and Hawaiʻi Island. It possesses traits that are cause for concern, including prolific seed production, adaptation to disturbed habitats, and the ability to establish persistent populations that can spread into open natural areas. Dense stands may compete with native vegetation, alter plant community structure, and increase fine fuels that can contribute to wildfire risk, potentially impacting tropical island ecosystems. Because of these invasive characteristics, planting or intentionally spreading this species is not recommended. Where suitable, choose a low-risk or native grass alternative. In areas where Themeda villosa is already widespread, landowners and landscapers should avoid using it in new plantings and help prevent its spread into uninfested natural and managed areas.
High Risk Traits:
- Elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Naturalized on Kauai, Oahu and Hawaii (Hawaiian Islands), Sri Lanka and probably elsewhere
- A disturbance and pasture weed, forming pure stands that may reduce productivity
- Hawaii State noxious weed
- Other Themeda species are invasive
- Forms pure stands
- Reproduces by seeds
- Seeds dispersed inadvertently in heavily trafficked areas, as a contaminant, by water and sometimes intentionally cultivated by people
- Resprouts after mowing and grazing
Low Risk Traits:
- Unarmed, but with irritating awns
- Young growth palatable to grazing animals
- Non-toxic, and young shoots edible to people
- Herbicides provide effective control
