Lepidium latifolium L.
Perennial pepperweed, or tall white-top, is a member of the Mustard family introduced from either southern Europe or western Asia. Its roots can grow to 10 feet deep, storing large amounts of energy for regeneration. New shoots emerge from both creeping root stalks and seed spread. Perennial pepperweed is similar to hoary cress (aka white-top) although it is significantly taller—it gets up to 4 feet high (in contrast, white-top is 6 inches to 2 feet tall). The lower leaves are oblong with toothed margins and have a waxy texture. The upper leaves do not clasp the stem as white-top does. Its heavy, sometimes woody crown has flowers that are four petaled, white, and densely clustered.
Perennial pepperweed can be found in pastures, riparian areas, roadsides, and disturbed areas. Once established, it will rapidly expand if left un-treated. Deep-seated storage rootstocks, waxy leaves, and stems make this weed difficult to control. Perennial pepperweed flowers from mid-summer to early fall.
Due to the severe threat that perennial pepperweed poses to the Snake River and wildlife habitat, please keep your eye out for this tall weed species as you explore Teton County.
If you find this weed on your property or around Teton County, please report it immediately at 733-8419.