Experiments on the activity of allogibberic acid on flowering are briefly described. After a preliminary mention of previous experiments on the quantitative enhancement of flowering of the SDP Chenopodium rubrum by allogibberic acid, observations were turned to Perilla ocymoides. This SDP showed a different behaviour towards allogibberic acid. In fact it reacted with a partial reversion of its developmental course, the inflorescences being affected (on account of the chemical treatment of the apex) by a sort of phyllody of the flower bracts. As it clearly appears in the inserted picture the plants at a certain point were looking as reverted to the vegetative phase (re-evocation of the vegetative morphogenesis) even continuously mantained under short day conditions. However the action seems rather limited, in our experiments, to the progressive enlargements of the flower bracts. A further acquisition in the matter regards—as only mentioned here—-the antiflorigenic activity of dehydrogibberic acid on the LDP Hydrophyllum virginicum. It appears possible that the antiflorigenic factor (or a component of a complex factor of this kind) may be different in different species even of the same photoperiodic category. It is well worth pursuing the search on the possible implications of the biochemical turnover of several morphogenins in flowering and inspect the possible coordination between their biochemical sequence and the seasonal sequence of the climatic factors or, anyway, the ontogenesis.