EPICOTYL DORMANCY IN SEEDS OF CIMICIFUGA-RACEMOSA AND HEPATICA-ACUTILOBA

Studies on the seed germination ecophysiology of Cimcifuga racemosa (L.) Nutt. and Hepatica acutiloba DC. revealed that both species have epicotyl dormancy. Radicles of seeds sown on soil in a nonheated greenhouse emerged in autumn, but emergence of cotyledons was delayed until later winter and early spring. Radicles of H. acutiloba seeds, incubated sequentially at simulated monthly temperature regimes, emerged in November and early December, but cotyledons did not emerge until February and March. After 165 days, radicles had emerged from 79% of the H. acutiloba seeds incubated at 20/10.degree. C, whereas cotyledons had not emerged after 245 days. Cotyledons did not emerge from seeds (with radicles emerged) of either species kept over winter in a heated greenhouse. Thus, chilling is required to break epicotyl dormancy. These two species can be added to the list of more than 20 species of herbaceous perennials of the Eastern Deciduous Biome whose seeds exhibit deep morpho-physiological dormancy.