P1. Syst. Evol. 182: 29-34 (1992) wPlant Systematics and Evolution © Springer-Verlag1992 Printed in Austria Cytogenetic study of F1 hybrids between Crepis dinarica and Crepis froelichiana (Asteraceae) DELPHINE CARTIER and SONJA SILJAK-YAKOVLEV Received December 4, 1991; in revised version April 27, 1992 Key words: Asteraceae, Lactuceae, Crepis dinarica, C. froelichiana. - Interspecific hybrids, chromosome infrastructure, C-banding. Abstract: Crepis dinarica and C. froelichiana are two closely related species of the C. praemorsa complex. Even though they exhibit the same chromosome number (2n = 8) and similar idiogram shape, they differ widely in quantity and distribution of heterochromatin bands. The hybrids between these two species comprise three morphological types. Parental genomes were distinguished in hybrids by Giemsa differential staining (C-banding). Al- though meiosis presents only a few abnormalities (about 2.4%), the percentage of aborted pollen grains is very high (90%). In previous papers (SILJAK-YAKOVLEV • CARTIER 1982, 1986) we compared four entities of the Crepis praemorsa complex: subsp, praemorsa L., subsp, corymbosa (GAuDIN) P. D. SELL = C. froelichiana DC., subsp, dinarica (BECK) HAYEK, and subsp, incarnata (WULF.) TAUSCH and concluded that they represent four distinct species [C. praemorsa (L.) TAUSCH, C.froelichiana DC. ex FROELICH., C. incarnata (JACQ.) TAUSCH, and C. dinarica (BECK) SILJAK-YAKOVLEV & WRABER]. These are well differentiated from geographical, ecological, and karyological points of view. Comparative analysis of their karyotypes showed that the distribution and quantity of constitutive heterochromatin differed extensively between them. In order to evaluate the relationships and degree of reproductive isolation of this closely-related group hybridisation has been carried out. In the present paper the hybrid between C. dinarica and C. froelichiana is considered. Material and methods Material collected in the wild was grown in the experimental botanical garden of Orsay University. Vouchers are deposited in the herbarium of our Laboratory. C. dinarica was obtained from Mt Crepoljsko, Yugoslavia (1440 m s.m.), and C. froeIichiana from Denti della Vecchia, Switzerland (1000m s.m.). Crossing was carried out by gently rubbing capitula together once or twice a day without emasculation. Mitotic chromosomes were studied in root-tip meristems, pretreated for 21/4 hours in 0.05% colchicine solution at room temperature, fixed in ethanol acetic acid (3:1) and stained using either the Feulgen method (FEULGEN& ROSSENBECK1924) or Giemsa C-