To provide the scientific basis for establishing the efficient cultivation and management measures of Torreya grandis cv.’Merrillii’,the process of the female flower bud differentiation was studied with the paraffin method.Results indicated that the ovulating strobilus differentiation of T.grandis cv.`Merrillii’ was mainly in the winter and the early spring.The ovulate strobilus formed in the middle and upper part of young tips of the mixed-bud.Their primordia appeared in early November before which there was no distinction in the dissected shape between the mixed-bud and the nutrition bud.Through the developments of bract,ovule scale,nucellus and integument,the strobilus started to blossom in the next mid-April and entered in a period of free nucleus of endosperm without formed female gametophyte and archegonium.The whole process lasted about 160 d.The illumination and themoisture in summer and autumn were main conditions to affect the female flower bud differentiation.
