ASPECTS OF CONE MORPHOLOGY AND DEVELOPMENT IN PODOCARPACEAE (CONIFERALES)

Ovulate cones in most Podocarpaceae consist of one or more fertile units, each composed of a fertile bract subtending an axillary epimatium that supports a single adaxial inverted ovule. Cones may consist of numerous units, up to ca. 20 in Microcachrys, but show progressive reduction in different taxa to the ultimate condition in which there is only a single pseudoterminal ovular unit. In the development of the ovular complex the solitary ovule arises from the surface of the preexisting epimatium. The sequence of parts is acropetal, rather than basipetal as previously reported. The consistency of the developmental process supports the hypothesis that the function of the epimatium is to produce an inverted ovule, essential for pollen scavenging via an extended pollination drop. Cone structure and position in relation to shoot construction, phenology of cone development, and correlation between the timing of development in cones and parent shoots are all shown to be interrelated.