Cytotypes within the family Umbelliferae with special reference to the genera Seseli L. and Oenanthe L. (subtribe Seselinae)

Abstract

Cytotypes within the genera Seseli L. and Oenanthe L. show variation in chromosome number in pollen mother cells. A correlation of low chiasma frequency with meiotic irregularities and pollen sterility was noted. In addition to the meiotic irregularities in the two genera occurrence of polyspory and triple pollen formation during meiosis have been observed in Seseli diffusum (Roxb.) Sant. Wagh. The presence of different chromosome numbers in different populations of the same species and karyological investigation in 4 species of Oenanthe L. suggests that structural changes of chromosomes associated with numerical differences have possibly played a role in their evolution. Diminution in chromosome size and complete absence of metacentric chromosomes in Oenanthe lachenalii Gmel. suggest that probably this species is more evolved than 3 species of Oenanthe (i.e., O. benghalensis Benth., O. pimpinelloides L. and O. thomsoni Clarke). The interrelationships of the two genera are discussed.