any of a genus (Lepidium) of small plants of the crucifer family, with small, whitish flowers and flattened pods, esp. the garden cress
See peppergrass in American Heritage Dictionary 4
noun
Any of several plants of the genus Lepidium, especially the North American species L. virginicum, having small white flowers and pungent foliage and seeds. Also called peppercress, pepperwort.