In northern Asia only few species exist which had been described under Thlaspi, but following my investigations since some years the greater part of them belong to the genus Noccaea MOENCH. The species, well-known as Thlaspi cochleariforme DC. since long time, receives a new nomenclatural combination as Noccaea thlaspidioides (PALL.) F. K. Mey. Plants of the arctic region, which till now were determined as Thlaspi-species described by DeCandolle, too, were found as members of a new species, Noccaea borealis F. K. Mey. It differs from N. thlaspidioides by its more gracile and smaller growing, the basal leaves have shorter petioles. They are as long as their leaf blade. Short subterranean shoots grow horizontally in the ground, while N. thlaspidioides has vertical taproots. Also the seed coats show differences. A near relative to these Siberian species is Noccaea japonica (H. BOISSIEU) F. K. MEY. which newly is combined here to the genus Noccaea. Not only with its broad and obcordate cauline leaves it shows its own features. To quite another relationship belongs the first as Thlaspi kamtschaticum Karav. described and later to Noccaea combined plant from the peninsula Kamchatka. But instead of all the species of Noccaea its fruits are no angustisept siliculae, but really siliquae with a relation between breadth to length as 1:5-6, and not as is said for the delimitation of siliculae with 1:3. The valves of the fruit are not folded from a keeled back, but lay plain over the dissepiment. So it was necessary to describe a new monotypic genus Noccaeopsis F. K. Mey. and to combine the only species as Noccaeopsis kamtschatica (KARAV.) F. K. Mey.