Freshwater green algae are one of the important sources of bioenergy in the future. Spirogyra is a conjugating filamentous zygnematacean green algal genus that is widely distributed worldwide with more than 400 species. Despite its widespread occurrence throughout the world, cytological studies of the genus have been limited. We investigated karyological features and chromosome numbers for seven Korean Spirogyra species. Most of the species examined in the present study showed significant karyological features, inner organization of nucleolus, heavily stainable nucleolar substance and the diffuse-centric nature of chromosomes, typical of the Conjugales. Chromosome number ranged from n=12 in S. varians to n=38 in S. africana. Aberrant cytokinesis resulted in binucleate and tetranucleate cells, which sometimes provide cytological explanation for different morphology and ploidal changes in clonal culture of Spirogyra or even different cells within the same filament. The present chromosome data also substantiates the earlier held assumption that aneuploidy must have been the chief driving force for speciation and evolution of the genus Spirogyra.

INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
  1. Interphase Nucleus
  2. General Pattern of Nuclear Division
  3. Cytokinesis
  4. Chromosome numbers
 DISCUSSION
 ACKNOWLEDGEMENT
 LITERATURE CITED

• Kim, Jee-Hwan(Centre of Advanced Study in Botany, Banaras Hindu University) Corresponding author
• B.R. Chaudhary(Centre of Advanced Study in Botany, Banaras Hindu University)
• Young Hwan Kim(Department of Biology, Chungbuk National University)
• In Kyu Lee(3School of Biological Science, Seoul National University)