Euphorbia heterophylla L. is a common weed in the South, Southeast, and Central West portions of Brazil. Chemical control is mainly done with herbicides that inhibit the enzyme Acetolactate synthase. However, resistant individuals have being observed in several farms of the South Region. There is no information about the genetic control of such resistance. The present work was aimed to study the hybridization technique in Euphorbia heterophylla L. It was studied the anatomy and the organogenesis of different individuals. Controlled emasculations and pollinations carried out in the stage 1(when the flowers present separate styles, erect and red, and ovary inside of the cyathium) produce great number of cyathium with one or two seeds and rarely three. The hybridizations carried out in the stage 2 (when the styles are separate and little reflex on the cyathium, turning from red to white, with the forked extremity, and ovary still included in the cyathium) or beyond this, do not affect the success of the hybridizations and the number of seeds.
hybridization; Euphorbia heterophylla L.; flower biology
