Karyomorphological Study of Some Selected Cycads

Karyotype and idiogram of three species of Cycas and Zamia from Nong Nooch Tropical Botanical Garden were obtained. All the three species of both Cycas and Zamia have an equal chromosome number in each species, namely 2n = 2x = 22 in Cycas and 2n = 2x = 16 in Zamia. The karyotype formulae of Cycas varied into 3 groups: 12 M + 8 SM + 2 A, 10 M + 8 SM + 2 A and 12 M + 8 SM + 2 T and of Zamia was 12 M + 4 SM. Of all three Cycas species studied, the karyotype of female and male plants could be distinguished. The Zamia evidence was complicated even all three species had the same chromosome number and karyotype pattern as well. Only Z. pumila could be differentiated between male and female plants.