Endogenous Rhythm in Opening and Odor of Flowers of Cestrum nocturnum

Abstract

Overland, Lillian. (Missouri Botanical Garden, St. Louis.) Endogenous rhythm in opening and odor of flowers of Cestrum nocturnum. Amer. Jour. Bot. 47(5): 378—382. Illus. 1960.–The opening and closing of flowers of Cestrum nocturnum have been found to occur in a cyclic manner both in constant light and constant darkness at constant temperature. The strong odor, which in nature occurs at night and was previously believed to be a direct result of darkness, has been shown to exist as an endogenous rhythm, occurring under constant conditions of temperature and light, as well as in darkness. Although in nature the odor cycle is so synchronized by the environment as to have a period of roughly 24 hr., in constant conditions temperature affects the cycle by lengthening it at low temperature and reducing it at high temperature. The cycle may be disrupted by shifting between extreme temperatures, but it is not destroyed. The controlling mechanism for odor production seems to be located in the tips of the corolla and the cycle exists independently in the excised tips.