Cytotaxonomic studies in five species of Rutidosis (Asteraceae) endemic to south-eastern Queensland

Abstract

Somatic chromosomes of five species of Rutidosis endemic to south-eastern Queensland were analysed by the aceto-orcein staining method. The five species were classified into two major groups by their basic chromosome number and asymmetry of chromosome length. Rutidosis glandulosa and R. murchisonii exhibited a basic chromosome number of x = 11 and a gradual change in chromosome length. Rutidosis crispata, R. lanata and R. leucantha exhibited a basic chromosome number of x = 12 and the karyotype was bimodal with respect to chromosome length. On the basis of chromosome evidence, we hypothesise that (1) R. glandulosa and R. murchisonii are closely related, (2) R. crispata and R. leucantha are closely related and (3) R. lanata is most likely to be derived from R. crispata by a hexaploidisation. The present results support Holland’s (1994, 1999) taxonomic treatment of the five species.