Premise: Nicotiana langsdorffii, Langsdorff's tobacco, is a species of the "Nicotiana" genus (tobacco). It is an annual plant with large leaves (up to 10 inches long) with tall 2 inch nodding long tubular bell shaped flowers that are apple green in colour, with blue anthers. "N. langsdorfii" lacks fragrance unlike some of the other tall species. It is grown as an ornamental garden plant.
Hypothesis:  Langsdorff's tobacco is a not a very good green plant