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Abstract Recent studies using regions of the nuclear and plastid genomes have shown that T. H. Goodspeed's sectional groupings in Nicotiana are for the large part upheld. However, we have shown that in several cases sectional membership should be revised. Here we present a revised outline of the sections of Nicotiana with lists of their component species. Relationships of the sections as defined can be seen in accompanying figures. Two sectional names with priority over those in current use are introduced ( N . sect. Polydicliae & sect. Petunioides ) and one new section, N . sect. Sylvestres , is described here. Two species names are changed to those with priority over those adopted by Goodspeed in his monograph of the genus: N. obtusifolia for N. trigonophylla and N. quadrivalvis for N. bigelovii . Synonymies are provided for each of these names. A short morphological description is provided for each section, along with a generalized distribution and a list of accepted species names.
Knapp et al. (Sun,) studied this question.