First recorded in 1555–65; pepper + wort2 (Source: dictionary.com)
Definitions of Pepperwort
any of various temperate and tropical aquatic or marsh ferns of the genus Marsilea, having floating leaves consisting of four leaflets: family Marsileaceae
any of several plants of the genus Lepidium, esp L. campestre, of dry regions of Eurasia, having small white flowers and pungent seeds: family Brassicaceae (crucifers)Usual US and Canadian name: peppergrass
A wild cress, particularly one with pungent leaves.