Article

A detailed cytoembryological study of seed development in the eight Bulgarian Thalictrum taxa showed that embryogeny conforms to the primitive Onagrad type and the endosperm is nucIear. Some advanced features were found in mature seeds, in which respect T. simplex subsp. rhodopaeum, by the formation of a primordial plumule and procambial vessels, appears to represent the highest evolutionary level known for the whole family. These and other data demonstrate that the evolution of cytoembryological features within the genus Thalictrum shows both parallelism and heterobathmy.