XVI International Botanical Congess

Chromosome numbers were examined in 23 of the 24 remaining populations of the endangered herb Rutidosis leptorrhynchoides in southeastern Australia. Northern populations are primarily diploid while southern ones are either diploid or tetraploid. Significant quadrivalent formation at meiotic metaphase I in the polyploids suggests autotetraploidy. Low frequencies of triploids and aneuploids with low pollen viability were also observed. Results suggest that recovery plans for Rutidosis must be mindful of the cytological structure of the species. Analysis of seedlings from five re-established sites originally sourced from wild tetraploid populations indicates elevated diversity of dysgenic cytotypes possibly due to gene flow from local diploid populations.