(Cortaderia jubata, Cortaderia selloana)
Cultivated worldwide as a horticultural specimen, Pampas grass is now a worldwide invasive species problem. Listed as one of Hawai`i’s Most Invasive Horticultural Plants by Division of Forestry and Wildlife of the Hawai`i Department of Land and Natural Resources, it is one of the few horticultural weeds listed on the state noxious weed list. Native to South America, the genus name Cortadera means â€œcuttingâ€ in Argentinean.
- A clumping grass with large plumes reaching up to 6 feet in height;
- Leaves are narrow and have sharp, serrated edges;
- Showy white to purple flower plumes (24 – 31 in) tower three times higher than the foliage.
- Dry leaves along with a build up of dead materials creates fire hazard;
- broad habitat requirements;
- will grow vigorously in nearly any soil, under low or high moisture regimes, in full sun or dense shade;
- forms dense thickets;
- 1 inflorescences can produce 100,000 seeds;
- Seeds are produced apomictically;
- wind, water, fire dispersed;
- may impact watersheds by changing the natural water cycle;
- mechanical control is difficult due to cutting blade edges.
- Kauai â€“ The two known populations have been eradicated. Outreach continues as new introductions may appear at any time.
- Oahu â€“ OISC is working to educate property owners where the few ornamental plantings of C. selloana exist, and requests that pampas grass be removed and replaced with non-invasive alternate plants.
- Maui â€“ Both species of pampas grass were planted as ornamentals in upcountry Maui, and Cortaderia jubata has spread to other yards, pastures, native forests and Haleakala National Park. MISC is working to control both species before they become widespread. Property owners can help by contacting MISC for free help in removing these plants.
- Molokai â€“ All known plants were in landscaping situations, which MoMISC controlled.
- Hawaii Island: As of 2020, all known populations have been removed.