ABSTRACT
Rudbeckia plants are perennial or biennial herbs of North American origin. Photoperiodic effects on growth and flower bud formation in Rudbeckia plants were first reported by W. W. Garner and H. A. Allard in 1923. Morphological aspects of Rudbeckia plants were described by N. L. Britton and H. A. Brown. Rudbeckia bicolor Nutt, and R. speciosa Wend, have often been used as experimental materials, especially in the investigation of flowering processes. Although many studies have been done using these species, the number of experiments which were conducted with a view to elucidate the effects on flowering of environmental conditions such as the photoperiod and temperature were rather limited. As far as the effects of temperature on plant growth and flowering in Rudbeckia are concerned, only a limited number of reports can be found.
