A variant of the Asiatic hybrid lilies (Lilium spp.), ‘Kiyotsubeni’, selected by a grower, was similar to the original form but displayed slight morphological differences. We determined that this variant form was a tetraploid/diploid periclinal chimera based on stomatal guard cells, pollen size, and chromosome number. Morphological and physiological changes associated with polyploidisation were identified by comparing diploid and chimeric forms (4×/2×) of ‘Kiyotsubeni’ under natural conditions and early forcing culture. Under early forcing culture, the chimeric form flowered earlier and displayed a shorter stem and broader leaves than the diploid form. The chimeric form also had a softer stem. Diploid ‘Kiyotsubeni’ was more susceptible to leaf scorch than the chimeric form. These results demonstrate that differences in ploidy influence agronomic traits and that the periclinal chimera (4×/ 2×) is effective for generating resistance against leaf scorch. ? 2005 Taylor & Francis Group, LLC.