any of 230 species of herbs constituting the genus Lepidium, of the mustard family (Brassicaceae), distributed throughout the world. Many, such as L. perfoliatum, are lawn and field weeds, but some are useful salad plants. Most species have long taproots, broad basal leaves differing from the narrow leaves on the flowering stalks, and spikelike arrangements of small, greenish or whitish, four-petalled flowers. Each seed is in a flat, round, dry fruit. Garden cress (L. sativum), a North African annual, is sometimes cultivated for its piquant basal leaves. Virginia peppergrass (L. virginicum), spread throughout North America, sometimes is known as canary grass because its seed stalks are fed to cage birds. Its leaves are used in salads. Lentejilla, or little lentil (L. intermedium), native to Europe but long naturalized in Mexico, is used as a folk medicine. Pepperwort, or field pepper (L. campestre), a widespread weed, is native in Europe and naturalized in North America. It has hairy, arrow-like stem leaves and once was marketed as an antidote to poisons under the name of mithridate pepperwort.