KARYOMORPHOLOGY OF SOME MORACEAE AND CECROPIACEAE (URTICALES)

The karyomorphology of 16 species in 13 genera representing Moraceae a nd Cecropiaceae was investigated in an effort to contribute to a bette r understanding of chromosome features and evolution in the families. All genera investigated have similar karyomorphology, but differences are found in (1) chromosome features of interphase nucleus (simple, si mple-complex, or complex chromocenter type), (2) basic chromosome numb er (x= 13 or 14), (3) size variation (mono-or bimodial), and (4) frequ encies of chromosomes with median centromeres (m-chromosome) (25-85%) and those with subterminal (or terminal) centromeres (st-chromosome) ( 14-69%). Comparisons with Ulmaceae as an outgroup of the remainder of Urticales suggest that the simple chromocenter type, x=14 comprising b oth m- and st-chromosomes, and the monomodial karyotype are plesiomorp hies in Moraceae and Cecropiaceae. Most of Moraceae and Cecropiaceae r etain generalized chromosome features of the order, but have involved a few evolutionary changes in karyomorphology. Based on some detailed karyomorphological data, inter- and infrafamilial relationships are al so briefly discussed.