Cultivated chrysanthemums, especially the greenhouse series of ‘Indianapolis’ cultivars, are probably periclinal chimeras for flower color. Therefore, in vitro propagation of chrysanthemum, which has recently been described, might produce plants not true to type. To test this, plantlets were generated from cultures of petal segments, petal epidermis, and shoot tips; these plantlets were grown to flowering to determine whether chrysanthemums with two genetically different chimeral layers in the petals are stable in tissue culture. Layer I displaced layer II in the formation of new meristematic areas in shoot tip and petal culture, showing that such chimeras are unstable in culture. Many more abnormal morphological types were exhibited by the plants which were regenerated from petal cultures rather than those from shoot tip cultures. Abnormalities included quilled and incised petal forms, as well as lack of anthocyanin pigmentation, characteristics which may not be attributable to the rearrangement of chimeral layers. Paramutation, true mutation, and environmenal effects are offered as possible explanations for this phenomenon.

Cultivated chrysanthemums, especially the greenhouse series of ‘Indianapolis’ cultivars, are probably periclinal chimeras for flower color. Therefore, in vitro propagation of chrysanthemum, which has recently been described, might produce plants not true to type. To test this, plantlets were generated from cultures of petal segments, petal epidermis, and shoot tips; these plantlets were grown to flowering to determine whether chrysanthemums with two genetically different chimeral layers in the petals are stable in tissue culture. Layer I displaced layer II in the formation of new meristematic areas in shoot tip and petal culture, showing that such chimeras are unstable in culture. Many more abnormal morphological types were exhibited by the plants which were regenerated from petal cultures rather than those from shoot tip cultures. Abnormalities included quilled and incised petal forms, as well as lack of anthocyanin pigmentation, characteristics which may not be attributable to the rearrangement of chimeral layers. Paramutation, true mutation, and environmenal effects are offered as possible explanations for this phenomenon.