XVI International Botanical Congess
Poinsettia (Euphorbia pulcherrima) is one of the leading floricultural crops commercially produced in the United States. Partly because of its economic importance, we have ongoing studies involving this crop. During the last five years we have used 'Freedom Red' in vegetative and flowering experiments. Occasionally we have observed atypical responses in leaf, bract, and flower develop- ment. Poinsettia requires short days to flower with bract formation and coloration preceding or coinciding with cyathia production. We have observed under long-day conditions, however, cyathia as terminal (apical) buds without bract formation. Irregular leaf dentation has also been noted on underfertilized stock plants. Examining the mechanisms for such atypical responses could redirect future research.