Photoperiodic Responses of Two Cestrum Species and Non-Interchangeability of Their Flowering Hormones.

Recently Lincoln et al. (2) isolated a fraction froml the leaves of induced Xanthiniiii struiarinin-i L. which, w-hen applied to the leaves of noninduced plants of X. pennsvlzvaniculn WVallr., caused formation of flower primordia. With this dliscovery it becomes nmore important that we examine various species to determine, if possible, whether a single flowering hormone is present in Angiosperms, or a series of such hormones. This report offers some evi(lence in this area. Evidence concerning photoperiodic response of Cestrbini octurinumt L. has been previously reported by Sachs (4). In his work it was demonstrated that C. noctutrnutin is a long-short day (LSD) plant; that the hormone is synthesized in mature leaves and is transported through the stem to the potential floral buds both acropetaly and basipetaly. This present investigation gives evidence that C. niocturnumi responds x-ith flow-er formation to a lonig day (LD) treatmiient as w-ell as to a LSD treatnment.