ABSTRACT
Pharbitis nil Choisy, the Japanese Morning Glory, has been one of the most intensively studied plants with respect to the conditions that influence its flowering. Pharbitis nil was first introduced into Japan from China in the 7th century. Pharbitis has a number of advantages as a model system for flowering studies and particularly for studies of the photoperiodic mechanism. Flowering in Pharbitis has frequently been used as a model system to study the macromolecular events related to differentiation. The flowering of a Pharbitis seedling is induced by a single photoinductive cycle, which allows the investigator to control a process of differentiation with a minimal, nonchemical stimulus. Pharbitis nil is a valuable tool for studies of photoperiodic induction largely because it can be induced by exposure to a single dark period longer than a critical duration and because it is sensitive at a very early stage of growth, 3 to 5 days after sowing.
