CYTOLOGICAL FEATURES OF THE ASTER AGERATOIDES COMPLEX (ASTERACEAE) INTAIWAN

Chromosome cytology was examined in two species of the Aster ageratoid es complex, A. ageratoides Turcz. (= A. leiophyllus Franch. et Sav.) a nd A. lasioclada Hayata, in Taiwan. Of the 70 individuals of A. agerat oides sampled, one was found to be diploid (2n = 18) and the rest tetr aploid (2n = 36, 37). The occurrence of the diploid A. ageratoides in Taiwan appears to be ancient. Eighteen individuals of A. lasioclada we re examined, of which 15 were diploids (2n = 18) and three triploids ( 2n = 27, 28). The triploid plants were not sympatric with tetraploid p lants and could not be distinguished morphologically from the diploids ; they may represent spontaneously occurring individuals with one unre duced gamete.