Black Henbane
Buffalobur
Canada Thistle
Common Crupina
Dalmatian Toadflax
Diffuse Knapweed
Dyer's Woad
Field Bindweed
Hoary Cress
Johnsongrass
Jointed Goatgrass
Leafy Spurge
Matgrass
Meadow Hawkweed
Meadow Knapweed
Milium
Musk Thistle
Orange Hawkweed
Perennial Pepperweed
Perennial Sowthistle
Poison Hemlock
Puncturevine
Purple Loosestrife
Rush Skeletonweed
Russian Knapweed
Scotch Broom
Scotch Thistle
Silverleaf Nightshade
Skeletonleaf Bursage
Spotted Knapweed
Syrian Beancaper
Tansy Ragwort
Toothed Spurge
Yellow Starthistle
Yellow Toadflax
Idaho OnePlan recommends the website of the
Idaho Weed Awareness
Campaign as the best resource for up-to-date information about
Idaho's noxious weeds, and their control.
Source for this page:
Idaho's Noxious Weeds
by Robert H. Callihan & Timothy W. Miller
BACKGROUND
Perennial pepperweed (Lepidium latifolium) is native to southern Europe and western Asia. It spreads by seed and creeping roots under many different environmental conditions.
DESCRIPTION
Perennial pepperweed grows up to 6 feet tall and has basalAt the base of plant or plant part leaves that are lance shaped, have long petiolesleaf stalks, are up to 12 inches long, and are covered with a waxy layer. Stem leaves are smaller and have shorter petioles, but don't claspLeaves that appear to wrap around the stem at their base the stem. Leaves have a prominent, whitish midveinThe center and usually most prominent vein on a leaf. Flowers are white, less than 1/8 inch wide, and are borne in dense, rounded clusters at the branch tips from early summer until fall. Fruits are roundish, slightly hairy, measure 1/16 inch in diameter, and contain 2 tiny seeds.
DISTRIBUTION
Perennial pepperweed is widely scattered throughout the U.S. and in many Idaho counties.
CONTROL
No biological control agents are available for perennial pepperweed, but herbicides are available to provide control.