The breeding systems of 22 species of Asteraceae were studied in Curitiba, Paraná, southern Brazil, in order to investigate the occurrence of spontaneous apomixis in subtropical representatives of this family. Controlled pollination experiments indicated seven species presenting fruits in the apomixis treatment (Calea hispida, Taraxacum officinale, Baccharis cylindrica, B. dracunculifolia, Chromolaena ivaefolia, Trixis verbasciformis, and Vernonia discolor), but only the first two with viable seeds. The remaining 15 species did not show fruits in the apomixis treatment: Bidens pilosa, B. tinctoria, Campovassouria cruciata, Chromolaena laevigata, Erechtites valerianaefolia, Hypochoeris radicata, H. tweediei, Lactuca scariola, Mutisia coccinea, Senecio brasiliensis, Sonchus oleraceus, Sphagneticola trilobata, Vernonia platensis and V. flexuosa showed spontaneous self-pollination, but in highly variable levels. Perezia cubataensis was the only species that did not show spontaneous self-pollination. Pollen viability tests showed very low proportion of sterile grains for all species, except for T. officinale and C. ivaefolia. The relatively small frequency of spontaneous apomixis in this sample of subtropical Asteraceae is remarkable, as it is the parthenocarpy (production and maitenance of seedless fruits) found in five species.
apomixis; Asteraceae; breeding systems; parthenocarpy
