Studies in Gentianaceae. I. Nodal Anatomy of Frasera and Swertia perennis

A comparative study of the nodal anatomy of Frasera and Swertia perennis revealed that, far from being uniform throughout, as would be expected from previous reports, it varied within genera, species, and even in individuals. 2. The variation pattern within individuals, however, was consistent enough in species and species groups for the recognition of five major types of nodal anatomy which could be used for purposes of comparison and classification. 3. Several important problems concerning the use of nodal anatomy in general, evoked by these findings, are discussed.