Article

Aspects of the reproductive biology of the 9 wild Iberian species of Sonchus and Aetheorhiza, plus one additional subspecies and an interspecific hybrid, have been studied. Comparison between fruit set in bagged and freely poliinated flower heads indicates that xenogamy is prevalent in most species, but that some taxa are preferentialIy autogamous. There is a clear correlation between reproductive system and life cycle. The {lollen-ovule index is similarly correlated but also shows clinal differences within single capltula. Xenogamy appears to be the primitive condition within the group. The evolutionary shift to self-fcrtility has entailed a change in flower head diameter, in floral pigmentation, and in longevity of the florets and flower heads. '