EN
A study of Gentiana cruciata L. (Gentianaceae), Gymnadenia conopsea (L.) R.Br. (Orchidaceae) and Luzula pedemontana Boiss. et Reut. (Juncaceae) showed differences in the number and characteristics of critical stages in ovule and seed development. The shared critical stages explain the general direction of the formation of reproductive structures and surrounding tissues. The taxon-specific critical stages may have different implications in a given species: they may (1) verify that the ovule belongs to a specific type, (2) indicate their lability in different taxa with the same ovule type, or (3) coincide in species with various ovule types.