Flowering is controlled by a variety of interrelated mechanisms. In many plants, the environment controls the production of a floral stimulus, which moves from the leaves to the shoot apex. Apices can become committed to the continuous production of flowers after the receipt of sufficient amounts of floral stimulus. However, in some plants, the commitment to continued flower production is evidently caused by a plant's commitment to perpetually produce floral stimulus in the leaves. Ultimately, the induction of flowering leads to the specification of flowers at the shoot apex. In Arabidopsis, floral specification and inflorescence patterning are regulated largely by the interactions between the genes TERMINAL FLOWER, LEAFY and APETALA1/CAULIFLOWER.