Degenia is a monotypic plant genus in the Brassicaceae containing the single species Degenia velebitica. Erysimum also belong to the Brassicaceae, so the flower similarity is due their close familial relationship. The genus Erysimum has 74 species, so is much more well known.
Peter George, Petersham, MA (north central MA, close to the NH/VT borders), zones 5b and 6 around the property.
Yesterday I took this picture of 3 of my Degenia velebitica plants, seedlings from my original plant located in a different part of the garden. They are two years old, and flowering very nicely this year. I should get quite a bit of seed, so if you're interested, let me know.