Florigen

Flowering hormone in plants

Florigens (or flowering hormone) are proteins capable of inducing flowering time in angiosperms. The prototypical florigen is encoded by the FT gene and its orthologs in Arabidopsis and other plants. Florigens are produced in the leaves, and act in the shoot apical meristem of buds and growing tips.

From Wikipedia, under CC BY-SA. More on occurri.