Article

A cytoembryological study of Crepis bithynica - a Balkan subendemic species from Pirin Mt., Bulgaria has been carried out. The major characteristics of the male and female gametophytes and the trends of evolution of the embryological structures and processes of C. bithynica were revealed. The anther wall develops according to the Dicotyledonous-type and it is four-layered with epidermis, endothecium, one ephemeral middle layer and ameboid tapetum. A reduction of the anther locules from four to two was observed. After simultaneous microsporogenesis predominantly tetrahedral tetrads are formed. The mature pollen is in a high degree fertile. The archesporium in the ovule is unicelullate. The embryo sac develops after basic Polygonum (monosporic)-type. Somatic apospory and integumentary embryony were observed. Some of the primitive embryological features correspond with the relatively primitive morphology of C. bithynica. The study reveals a relatively high specialization and plasticity especially of the female gametophyte. This provides better trophical function, larger adaptability and successful reproduction, thus supporting the potential possibilities for survival and expansion of the populations of C. bithynica.