Identification (general): Exotic ornamental grasses have become popular in landscaping on the mainland and some are being used here in Hawai'i. A number of these ornamental grasses have been found to be invasive. Some invasive ornamental grasses recently seen on Oahu are: Pampas grass (Cortaderia selloana and C. jubata), feathertop fountain grass (Pennisetum villosum), Mexican feather grass (Nassella tenuissima), Japanese blood grass (Imperata cylindrica), and pink crystal glass (Melinis nerviglumis). Ornamental grasses usually have showy flowers or seedheads.
Impacts: Exotic grasses are often fire-adapted, meaning they provide fuel for brushfires and reproduce better after being burned. Many exotic grasses are unpalatable to livestock and can ruin pastures. Because of these threats, the Oahu Invasive Species Committee recommends to voluntarily avoid planting any type of ornamental grass in their landscaping as the best preventative measure.
Dispersal Mechanism: The same features that make the flowers and seed heads of ornamental grasses attractive for landscaping (feathery or brush-like projections) are also responsible for their easy dispersal by wind; seeds can be carried far from the parent plant and easily spread into forests and natural areas. Some species can also spread vegetatively by way of creeping, underground stems or when construction equipment or soil contaminated with broken stems is moved and brought to a new location.
Funding and support for this project was made possible by the Hawai'i Invasive Species Council, the USDA Forest Service State and Private Forestry assistance, and University of Hawai'i-Pacific Cooperative Studies Unit.