Karyotype Analysis of some Formosan Gymnosperms

Karyotypes of 13 species of 9 genera and 3 families of gymnosperms have been studied. The chromosome number and/or karyotype analysis of 6 species had been reported by previous workers. The karyotypes of the remaining species are reported here by the present authors for the first time. The diploid chromosome number in Pinaceae is 24, while it is 22 in both the Taxiodiaceae and Cupressaceae. For all Formosan species, the karyotypes of Pinus are similar. The secondary constriction of a chromosome may be a useful character for identification of species. SAT-chromosome have been found in the genus Cunninghamia. The karyotypes of Pinus are symmetrical while they are asymmetrical for the other genera of Pinaceae. Pinus is considered to be the most primitive taxon among genera of Pinaceae. A key for identification of these genera based on their karyotypes has been prepared.