Abstract: Changium smyrnioides Wolff is an endangered species of the monotypic genus Changium (Umbelliferae). For a better understanding of its genetic diversity, four populations of this species were cytologically and allozymically investigated. The karyotypic analysis of C. smyrnioides indicated that the chromosomal number was stable (2n = 20) in all populations. Karyotypes of the populations were all “2A” type. Karyotypical polymorphism was shown as the chromosomal heterozygosity, and position shift of the satellite. Genetic diversity of 4 populations was analysed with starch gel electrophoresis. A low level of allozymic diversity was estimated based on 19 loci of 10 enzyme systems. Genetic diversity within 4 populations was relatively low with the proportion of polymorphic loci (P) ranging from 19% to 42.9%, average number of alleles per locus (A) from 1.2 to l. 7, mean expected heterozygosity ( H_e ) 0. 073 and mean observed heterozygosity ( H_o ) of O.030. In general, about 58% of genetic variation were attributed to the differentiation among populations, while the remaining 42% resided within populations. The genetic diversity of the eastern populations was higher than that of the southwestern populations. On the basis of this studies, we thought that the habitat of C. smyrnioides should be protected and most of the populations should be sampled soas to retain as much genetic diversity as possible in ex-situ conversation.

Key words: Changium, Karyotype, Allozyme, Genetic diversity, Conservation biology