Erysimum menziesii subsp. yadonii, or Yadon’s wallflower, is endangered, so it is likely that this image is the closest that you and I will ever come to seeing the plant–it doesn’t seem to be in cultivation. From what I’ve been able to discern, it is found in only one locale in the world (the coastal sand dunes near Marina, California). It has the dubious distinction of receiving California’s highest designation for endangered organisms, S1.1. The .1 means “very threatened”, while S1 means “Less than 6 Element Occurrences (EO) OR less than 1000 individuals OR less than 2000 acres”. Lastly, an EO is roughly defined as an area of land and/or water in which a species or natural community is, or was, present.