The flowers of Winteraceae show great diversity in number and arrangement of organs. In most genera of Winteraceae a continuity of initiation from sepals through petals, stamens, and carpels results in relatively few floral arrangements, these being variations on decussate and whorled patterns. However, a diversity of phyllotactic patterns is found in the flowers of Drimys winteri, resulting from the unconstrained placement of petal primordia following a delay between sepal and petal initiation. In all taxa there is within-pattern variation in divergence angle and plastochrone ratio correlated with the eccentricity of the floral meristem. Differences in floral form define the genera of the Winteraceae and these differences are controlled by the timing and duration of primordial initiation, the position of initiation of the primordia, the shape of the floral meristem, and the relationship between size of meristem and size of primordium. An understanding of these ontogenetic processes is important in understanding diversity and evolution of floral form in Winteraceae.

Key words: floral development, phyllotaxis, Winteraceae