XVI International Botanical Congess

Themidaceae (formerly Brodiaeae of Alliaceae) consists of 11 genera and 61 species of lilioid geophytes. Generic circumscriptions within the family are controversial because they focus on one or two key morphological characters (e.g., the presence of a perianth tube). Phylogenies from morphological and four molecular datasets support none of the conventional views and demonstrate the need for new generic circumscriptions. In addition, Themidaceae contains several examples of polyploid speciation associated with endemism to islands, serpentine soils or other unusual substrates. In a lower-level study on progenitor-derivative taxon pairs, chromosome painting (FISH) is being used to identify the parental chromosomes of allopolyploids and to paint rDNA and other loci on individual chromosomes. Fluoresced loci serve as markers in chromosomal structural evolution and assist in determining orthology of DNA sequences used in phylogeny reconstruction.