Plants have a tendency to fl ower if placed under unsuitable growth conditions. A review of the literature reporting such nonphotoperiodic fl owering indicated that most of the factors responsible for fl owering could be regarded as stress. Those stress factors include poor nutrition, high or low temperature, high-or low-intensity light, ultraviolet light, and many others. This fl owering would be called stress-induced fl owering. The plants that were induced to fl ower by stress reached anthesis, produced fertile seeds, and the progeny developed normally in Pharbitis nil and Perilla frutescens var. crispa . Grafting experiments using two varieties of P. nil revealed that a transmissible fl owering stimulus is involved in stressinduced fl owering. Salicylic acid and/or the fl owering gene FLOWERING LOCUS T may be involved in the stress-induced fl owering of P. nil , P. frutescens , Arabidopsis thaliana , and Lemna paucicostata . The stressed plants do not need to wait the arrival of a season when photoperiodic conditions are suitable for fl owering, and such precocious fl owering might assist in species preservation. Thus, stress-induced fl owering might have a biological benefi t and should be considered as important as photoperiodic fl owering and vernalization.