Perennial Pepperweed

Perennial Pepperweed (PPW) is a noxious weed and perennial forb that is native to West Asia and throughout Southeastern Europe. It will grow in almost any habitat but its native range includes fresh, brackish and saltwater wetlands, agricultural fields and surrounding areas and even stony slopes. PPW is widespread through the western Unites states and was possibly introduced through a contamination of sugar beet seeds and or alfalfa fields and rangelands. PPW has established itself on Long Island at Westmeadow Beach and Flax Pond, possibly due to feed from adjacent horse show grounds that brought feed that was likely contaminated with PPW seeds or root fragments.

PPW can grow 3-8 ft tall and initially shoots up from a rosette near the soul’s surface. Its basal leaves are 4-12 inches long and 1-3 inches wide. The leaf area is smallest as the PPW grows and begins to flower. The flowers of PPW are arranged in a loose branching cluster made up of tiny white 4 petal flowers that are 3mm wide. The fruit of PPW is in the form of a narrow pod that drops at irregular intervals throughout the winter and can be dispersed through wind, water or animals. PPW can produce thousands of seeds per individual plant specimen. They also have a creeping root system with semi-woody root crowns that make up 40% of the plant’s biomass that can grow as far as 9 ft. deep. The root and root crown fragments are highly reproductive and can easily spread through the tides to establish new colonies and can also tolerate very dry conditions.

The extensive root system of this plant allows it to uptake nutrients deep within the soil such as Calcium and Sodium which can affect the soil chemistry and furthermore, decrease plant diversity by inhibiting the native plants ability to survive. PPW can also spread clonally and can threaten the stability of a marsh ecosystem or, as it has in the west, threaten the agricultural fields by decreasing the value of usable land and be hard to maintain or control as it is a poor forage crop.

Early detection and early response are the strongest management practices for PPW. Small populations have found success with hand pulling and removing as much of the root as possible. For established or larger populations of PPW, mowing and cutting used in combination with herbicide treatment of glyphosate is useful. However, this method is not recommended in areas near wetlands. Planting a native plant like saltgrass or spike grass may outcompete PPW and suppress PPW growth. There is research currently being done to find a suitable biocontrol for PPW however further research is needed to determine success for managing and reducing PPW populations.

Resources

Perennial Pepperweed – LIISMA Species Profile, This webpage from the Long Island Invasive Species Management Area (LIISMA) provides information about the history and introduction of this plant species, its identification as well as the damage it causes to the Long Island ecosystem and current control methods to prevent further spread and removal of the species.

Forest Service FEIS – Broadleaf Pepperweed, This database page from the Fire Effects Information System from the Forest System provides readers with a wealth of information about this species on a national and local scale. It covers its distribution throughout the United States, its botanical and ecological characteristics, response to fire or fire ecology and adaptations and various management considerations. 

Last updated April 13, 2022