A synopsis of the South American Lepidium (Brassicaceae)

fifty native and 12 naturalized species of lepidium grow in south america, and a key to all 62 species is presented. three new species from argentina (l. hickenii, l. pedersenii, and l. santacruzensis) and two from peru (l. cuzcoensis and l. werffii) are described, illustrated, and their relationships to nearest relatives are discussed. the new combination lepidium crassius is proposed. furthermore, 19 taxa (coronopus didymus var. macrocarpus, c. didymus var. procumbens, l. abrotanifolium var. steinmannii, l. affine, l. argentinum, l. auriculatum, l. bonariense var. pseudovirginicum, l. calycinum var. integrifolium, l. costaricense, l. cumingianum var. orbiculatum, l. cumingianum subsp. berteroanum, l. depressum, l. myrianthum, l. neglectum, l. parodii, l. pubescens var. fallax, l. subvaginatum, l. virginicum subsp. centrali-americanum, thlaspi campestre) are lectotypified and 17 others (coronopus leptocarpus, c. leptocarpus var. microcarpus, l. boelckii, l. bonariense var. gayi, l. bonariense var. pseudovirginicum, l. brevicaule, l. calycinum, l. danielsii, l. demissum, l. kalenbornii, l. morrisonii, l. peruvianum, l. philippianum var. boliviense, l. raimondii, l. scabrifructum, l. spicatum var. caylx-persistente, l. subvaginatum) are reduced to synonymy. l. depressum and l. rahmeri are new records for argentina.