Lepidium latifolium

Leaves are alternate, oval to lance-shaped, mostly 3-12 in. long, 1-3 in. wide, green to gray-green, lack hair and waxy; edges (margins) smooth to toothed and can also be curled. Flowers are small and white with 4 petals; arranged in dense clusters at the tips of stems. Seed pods are round, flattened, less than 0.1 in. diameter, usually covered with hairs; each has 2 chambers, each with 1 seed. Perennial pepperweed grows very aggressively, forming dense colonies that exclude native species. It reproduces both by seed and vegetatively from its roots and small root fragments. Seeds and root fragments are spread easily by flooding and soil movement, and seeds stick to tires, shoes, and animals, making continued dispersion difficult to avoid. Perennial pepperweed also increases soil salinity, reducing germination of many desirable species. It is a state-listed noxious weed in California and many other western states.