Perennial pepperweed
Lepidium latifolium

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Pictures of perennial pepperweed     Photo courtesy of:  http://tncweeds.ucdavis.edu/esadocs/lepilati.html

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Common names: broad-leaved peppergrass, tall whitetop, Virginia pepperweed, perennial pepperweed, broad-leaf peppergrass

Description: The perennial pepperweed is an aggressive weed that establishes and colonizes very rapidly.  It usually grows from 1 to 3 ft. and possibly up to 6 ft. tall.  The weed has white flowers that grow on top of the plant.  This weed was probably introduced into the United States around 1900 from contaminated beets.  This plant degrades the nesting area for wildlife and pushes them into other fields where they are unwanted. This noxious weed can tolerate salty soil very well and begins to infest very rapidly.  (1,2,3,4,5)

Habitat: Originally native to southern Europe and also to western Asia the pepperweed is now mostly known to grow on the west coast of the U.S.A. (1,3,4,5)

Seeds: Each plant produces a small waxy fruit that does not open but falls regularly during the winter season. Each one of these little fruit bares 2 little seeds that are released when the fruit drops down from the plant.  The seeds that are dropped are round, flattened and slightly hairy. They measure 1/16 of an inch in length and are reddish brown colored. Perennial pepperweed can produce up too 6 billion seeds per acre. (1,2,5)

Leaves/Stems:  The waxy leaves are bright green to a gray waxy color. The leaves on top may have smooth or toothed margins. Stem leaves are larger and are stalked where upper leaves toward the top of the plant are shorter with shorter stalks. The larger leaves can grow off the stem to up to 12 inches long.  All of the leaves have a noticeable white vein running through them. (1,2,3,4,5)

Roots: The long extensive root system sends many shoots up in late winter or autumn and makes a large patch or infestation of the plant. The roots do not hold soil together very well so they are known to be a problem by increasing erosion on river banks, streams, and ditch banks. (1,5)

Flowers: Flowers in big dense clusters sitting on the very top of the weed. Every flower has 4 sepals and 4 petals. The seeds are often held on the plant and dropped during the winter. (1,5)


Environments Favorable to Infestation: It is known to be a problem on the roadsides, rangeland, field crops, riversides or on mountain tops. (1,4,5)


Chemical Control:  Glyphosate + 2,4-D was found to be 100% effective when applied to pepperweed periodically over 3 months. (2,4) Please consult your County Weed Supervisor or Extension Agent. Read the label on all herbicides before use.


Cultural Control:  There is only 1 partially effective cultural control: hand pulling and digging (wear gloves!). Since the roots are very extensive it is crucial that you pull the plant before the plant has grown seeds.  Make sure that after the plant has been pulled, all roots have been removed or dug up and desposed of in a land fill. (1,2)


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Links:

http://www.oneplan.org/Crop/noxWeeds/nxWeed19.htm
http://www.agf.gov.bc.ca/cropprot/weedguid/pepperweed.htm
http://www.nps.gov/plants/alien/fact/lela1.htm
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74121.html
http://www.invasive.org/browse/subject.cfm?sub=5931
http://threatsummary.forestthreats.org/threats/threatSummaryViewer.cfm?threatID=192

Bibliography: 
1.  Lisa Lantz and Bridget Simon, Perennial Pepperweed (Lepidium latifolium), (online), available, http://www.nwcb.wa.gov/weed_info/pepperweed.html.

3. Government of British Columbia, Field Guide to Noxious and Other Selected Weeds of British Columbia, (online) available, http://www.agf.gov.bc.ca/cropprot/weedguid/pepperweed.htm.

4. Fred Bentler, Perennial Pepperweed (Lepidium latifolium), (online), available, http://dnr.metrokc.gov/wlr/lands/weeds/peppweed.htm.

5. Yolo County Resource Conservation District, Perennial Pepperweed (Lepidium latifolium), (online), avaliable, http://www.yolorcd.org/weeds/pepperweed.shtml.

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By:  Toby Marx and Jim Thorne 4/20/04.  -   Updated by Lizzie and Markie 3/09.

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