A survey of pollen mitosis within permanent pollen tetrads of the primitive ranalean family Winteraceae revealed that two types of division, synchronous and asynchronous, are present. In the synchronous type, all four pollen grains are at exactly the same stage of division during formation of generative and vegetative (tube) nuclei and comparatively large cytoplasmic connections link the members of a tetrad. In the asynchronous type, all four pollen grains are not at exactly the same stage of nuclear division and cytoplasmic connections are absent between members of a tetrad. Each type is restricted to a particular taxon, but many species of Winteraceae have yet to be examined for this feature. Asynchronous division occurs inDrimyssect. Drimys andPseudowinteraand synchronous division occurs inBelliolum, Bubbia, ExospermumandZygogynumand probably inDrimyssect. Tasmannia (syn.Tasmannia) too. There is evidence inPseudowinterathat the asynchronous type has evolved from the synchronous. The adaptive significance of the two types is not obvious.