Jeren Fasihi - Department of Plant Science, School of Biology, College of Science, University of Tehran
Shahin Zarre - Center of Excellence of Living Organisms in Iran and Department of Plant Science, School of Biology, College of Science, University of Tehran, P.O. Box. ۱۴۱۵۵-۶۴۵۵.
Nasim Azani - Department of Plant Science, School of Biology, College of Science, University of Tehran.
Yasaman Salmaki - Center of Excellence of Living Organisms in Iran and Department of Plant Science, School of Biology, College of Science, University of Tehran, P.O. Box. ۱۴۱۵۵-۶۴۵۵.

The somatic chromosome numbers and karyotype features of ۱۵ species of Euphorbia (Euphorbiaceae) from Iran were analyzed. The chromosome counts of four species including E. inderiensis (۲n=۱۸), E. polycaulis (۲n=۱۸), E. phymatosperma (۲n=۱۶) and E. gypsicola (۲n=۵۴) are reported for the first time, while the chromosome number of ۱۱ more studied species are confirmed. We also confirm the occurrence of two different cytotypes in E. microsciadia: one diploid (۲n=۱۸) and the other tetraploid (۲n=۳۶). The karyotypes are often symmetrical composing mainly of metacentric and submetacentric chromosomes. The results also confirm the presence of different basic chromosome numbers including x= ۷, ۸, ۹ and ۱۰ within the genus, indicating the potential evolutionary importance of such data in the genus.

Cytotypes, Euphorbia, flora of Iran, karyology, Taxonomy, Evolution