The internal transcribed spacer (ITS) region of the nuclear ribosomalDNA was sequenced from 21 accessions of Viguiera from South America,including 14 from Brazil. Overall there was only a small amount of sequencevariation, less than 3.4% among South American samples and less than4.5% between the South American samples and the Mexican V. flava. Phylogenetic analysis revealed little divergence among the Braziliansamples of Viguiera. The low level of ITS sequence variation wasin striking contrast to the taxonomic diversity and chemical variability thathave been reported for Viguiera in Brazil. The low level of sequencevariation suggests that, despite its clear morphological and phytochemicaladaptations to the cerrado, Viguiera is probably a relatively recentaddition (less than 3 million years) to the flora of this area.
