Lepidium galapagoensis is described, and its distinguishing characters from all of the New World species of Lepidium are discussed. The species is readily identified by a combination of two stamens, elliptic and wingless fruits, short styles exserted from the apical fruit notch, and bimodal trichomes, of which those on the stems are minute and recurved and those on the leaves are distinctly larger and restricted to the margins of otherwise glabrous blades and petioles.