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Home>Plant Species>Weed Species>Perennial pepperweed

Drawing of perennial pepperweed Perennial pepperweed
Lepidium latifolium

question markDid you know?

Roots as deep as 9 feet make this weed difficult to control!

How did perennial pepperweed get here?
Perennial pepperweed is native to southern Europe and western Asia but is now found in many parts of the United States. It was probably introduced to North America several times, possibly as a contaminant of sugar beet seed, imported from Europe. It has been declared a noxious weed in many western states. Other names are tall whitetop and Virginia pepperweed.

What are its characteristics?
Perennial pepperweed persists as a rosette near the soil surface for several Perennial pepperweed flowersweeks before stems grow tall. It grows 1 to 3 feet tall with bright green leaves. Flowers are white, in dense clusters near the top, occurring from summer to fall. Roots as deep as 9 feet make this weed difficult to control. Each mature plant can produce thousands of seeds each year, but it more commonly reproduces through laterally creeping roots. Roots and seeds float and can be transported long distances by water to establish new populations.


Perennial pepperweed plant next to a man

Why is Perennial pepperweed a problem in the Great Basin?
Perennial pepperweed is invasive primarily in riparian areas and wetlands, yet may invade adjacent areas once established. Its extensive creeping root system increases competitiveness for water and nutrients while increasing nutrient storage for rapid growth in the spring. Perennial pepperweed stands can grow more than 50 stems per square yard, making it too thick for waterfowl nesting to occur.

How can we fight this weed?
Eradication of perennial pepperweed is no longer an option in western North America, and control efforts for perennial pepperweed have been largely unsuccessful. Perennial pepperweed can store large amounts of resources in its roots and can sprout stems following cutting, grazing, or herbicide treatments. Therefore, early detection and quick removal of perennial pepperweed populations increases the probability of successful control. Disking alone is also not effective because new plants sprout from root fragments. Grazing with goats and sheep is most effective in long term suppression of perennial pepperweed if started before all perennial grasses are lost from the community.

Images:
-Drawing: Michael B. Piep © 2006.
-Flower: Steve Schoenig CDFA.
-Plant: Steve Schoenig CDFA.

Text references:
-USDA, NRCS. 2006. The PLANTS Database (http://plants.usda.gov, 26 September 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
-Whitson, T. D., et.al. 2000. Weeds of the West., 9th ed. Western Society of Weed Science, Newark, CA.
-Zouhar, Kris 2004. Lepidium latifolium. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: (http://www.fs.fed.us/database/feis/, 26 September 2006).