Abstract
Mitotic chromosomes of seven South American species and two varieties of Lycium sect.Lycium were studied to clarify their taxonomic relationships and to assess the karyotype for possible insight into the evolution in the section. All species have 2n = 2x = 24. The chromosome numbers of L. infaustum and L. rachidocladum are reported for the first time and data on karyotype composition are mostly new. The generalized karyotype of the section shows it is highly symmetrical. The chromosomes are metacentric or submetacentric with the formula : 11 m + 1 sm. Microsatellites are present in chromosome pair #1 and are attached to the short arms. The section is karyotypically homogeneous. Cluster analysis using several cytological data and chromosomal identity index (CI) shows that most of the taxa are very close or even identical. There are no indications of major chromosomal rearrangements within the section. Karyotypic features obtained suggest that morphological differentiation in the group was not followed by chromosomal divergence.
