Abstract
Plants showing intermediate features between Sisyrinchium rosulatum BICKN. and a pale-purple flowered race (L-race) occur on the university campus of the authors. Based on morphological and cytological studies it was confirmed that these plants are natural hybrids between S. rosulatum and L-race. S. rosulatum, L-race and their hybrids had 32 chromosomes in mitotic cells, but their hybrids were sterile and showed a multipolar division in PMC and a low pollen fertility. L-race may be a related but separate taxon of S. rosulatum. Genetic investigation of flower color indicated that the white is dominant over the purple by a single Mendelian factor in S. rosulatum. Flower color variation in S. rosulatum may have resulted from the polymorphic occurrence of flower color controlled by major gene (s) and natural hybridization with the related species.
