Common pepperweed

Description

Lepidium densiflorum is a species of flowering plant in the mustard family known by the common names common pepperweed and prairie peppergrass. It is a common and widespread plant in North America, where it grows in many habitats across Canada and the United States.Lepidium densiflorum is an annual or biennial herb producing a short, erect, branching stem up to about 30 centimeters in height. Leaves grow in a basal rosette at the base of the stem and reach up to about 10 centimeters long; leaves higher up on the stem are smaller and less prominently lobed. The plant produces raceme inflorescences of tiny flowers with sepals each only about a millimeter long. There are usually no petals, though sometimes vestigial petals appear near the sepals. The fruit is a few millimeters long. The origin of Lepidium densiflorum is not entirely clear: some believe it was introduced in Europe or Eurasia, some believe it originated in western North America and east of the Mississippi River, and others believe it originated in the east. It is more likely that the species is native to North America and it was first discovered in a rubbish dump in Turku, Finland, in the early 20th century, but its distribution has expanded and it was considered a noxious and invasive herb in many states.