With plumes that bring to mind ostrich feathers, pampas grass first became popular in the Victorian era. Fluffy seed heads decorated the most fashionable hats, homes, even carriages. Interest surged again in the mid-1960s and the plant became a fixture in some yards and golf courses on Maui.

Today, pampas is taking over Instagram feeds: the plumes are used to add a Bohemian/Southwestern flavor to wedding bouquets, centerpieces, and home décor. But here on Maui, this ornamental grass is associated with a different trend: loss of habitat for threatened and endangered species and destruction of the watershed.

“But here on Maui, this ornamental grass is associated with a different trend: loss of habitat for threatened and endangered species and destruction of the watershed.”

Pampas is a clumping bunchgrass native to South America. The leaves are razor-sharp, dying back each year but leaving dry foliage that accumulates and can fuel wildfires. The decorative plume is the seed-head and a single plant can spread millions of tiny seeds on the wind – in some cases, as far as 20 miles. Seeds germinate readily on bare soil, but with enough moisture, the invader finds footholds in patches of moss or tree bark. The plant competes with native vegetation and could replace habitat and food resources used by native birds and in doing so disrupting the layered structure of the rainforest so important for aquifer recharge.  

This grass knows no limits – it has been found growing from sea-level to the rim of Haleakalā Crater at 9000 feet. Water, or lack thereof, doesn’t seem to be a key determinant for where pampas lives. It will (and does) grow in the wettest rainforests and on the driest hillsides, often emerging in rain-drenched bogs and wind-scoured cinder slopes.

Pampas grass has been a target for eradication on Maui since the mid-1990s when staff from Haleakalā National Park started finding feathery plumes in the crater. MISC has been working to stop pampas since the inception of the program. Through continued control efforts, the East Maui population has been in steady decline but without consistent support and control efforts, progress could stall.

The West Maui pampas population has always presented challenges. Much of the difficulty lies in the rugged terrain and weather, limiting access for much of the year. On East Maui, crews can access much of the known pampas infestation by timing helicopter flights early in the day and camping and hiking to access plants from the ground, but the slopes of the West Maui Mountains are more vertical than anywhere else in Maui, affording few camping sites and making ground access difficult or impossible. Pampas, on the other hand, thrives on the bare soil of the erosion-prone slopes. When that happens, our crews depend on helicopters to seek out and remove the invader.

Thanks to funding from the National Fish and Wildlife Foundation, MISC crews have been scouring the cliff faces of West Maui over the last year. They are looking for pampas plumes and the tell-tale growth pattern of the plant before it goes into flower. If they find the plant, they record the location by on a GPS and then return by helicopter but this time loaded down with an external tank and 80’ long line and weighted sprayer attached. This allows the pilot and crew to hold hover over the plant and remotely trigger a tiny spray of herbicide directly to the grass below.

Despite nearly constant rescheduling of flights due to weather or a need for the helicopters to go fight a brush fire, crews have flown over 15,000 acres on West Maui from 2017 to the summer of 2019. This coverage has led to the detection and removal of nearly 1,900 pampas plants from the mountain slopes– a huge leap forward in the effort to stop this invader from taking over prime habitat for native birds, plants, and invertebrates.

You can help. First, become familiar with what pampas grass looks like (mauiinvasive.org/pampas/). Second, never plant pampas grass or import it for décor or floral arrangements. The Division of Forestry and Wildlife has designated pampas as one of Hawaiʻis most invasive horticultural plants. Finally, report any pampas grass you find. You can report it to MISC: 573-6472, miscpr@hawaii.edu, or online at 643PEST.org

Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy, and quality of life.

This article was originally published in the Maui News on September 14th, 2019 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

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