 The reported absence of the diterpenes led Richard Spjut to conclude that a key difference in "V. tuberculata" was the absence the diterpenes; (-)-16 α-hydroxykaurane however, upon preparing to return specimens on loan from the University of Colorado Herbarium at Boulder, he noted two specimens from the type locality that had been determined by him to have (-)-16 α-hydroxykaurane with only trace amounts of zeorin.Evidently the authors in the original publication may have confused (-)-16 α-hydroxykaurane with zeorin.A correction by Spjut was noted on World botanical Associates web page.