Hair morphology and the relationships of species in Solanum sect. Basarthrum.

The usefulness of features of leaf hairs in distinguishing subgenera and sections is well documented in both Rhododendron and Solanum. In this analysis of the taxa of Solanum sect. Basarthrum (23 species), and of a sample of closely related taxa from sect. Petota (22 species), it is shown that such features serve to delineate subsectional groups such as series and some species as well. Section Basarthrum has an unexpected diversity of hair types. Although this group has been characterized by 2-celled 'bayonet hairs', more than one half of the taxa in the section bear multicellular 'finger hairs', and 3 species also possess branched hairs. Thus, major rearrangements of the species previously assigned to sect. Basarthrum are indicated or supported by pubescence features. The taxa studied from series Etuberosa and Juglandifolia (both of sect. Petota) show hair types that a) are relatively primitive for the section, and b) show linkage between sects. Petota and Basarthrum. [ABSTRACT FROM AUTHOR]