COMPARATIVE FLORAL ONTOGENIES AMONG PERSOONIOIDEAE INCLUDING BELLENDENA (PROTEACEAE)

Floral ontogeny is described and compared in five species and four gen era of the hypothetically basal proteaceous subfamily Persoonioideae s ensu Johnson and Briggs. The hypotheses surrounding the origin of the peculiar proteaceous flower and homologous structures within the flowe rs are examined using ontogenetic morphological techniques. Ontogeneti c evidence reveals that the proteaceous flower is simple, composed of four tepals, each tepal initiated successively with the lateral tepals being initiated first and second followed by the successive initiatio n of the sagittal tepals. Each of four stamens is initiated opposite a tepal in a similar sequence to tepal initiation. A single carpel deve lops terminally from the remaining floral meristem. In taxa of Persoon ieae, nectaries are initiated from a broadened receptacle in alternist amenous sites after zonal growth beneath and between the tepals and st amens has begun. The nectaries are interpreted as secondary organs, no t reduced homologues of a ''lost'' petal or stamen series. Development al variation is present among the examined taxa in several forms inclu ding the development of a Vorlauferspitze (spine) on the upper portion of the tepals, adnation between the anthers and tepals, and formation of the carpel. In Placospermum the early formation of the carpel clef t extends to the floral receptacle and in the other taxa, the carpel c left is distinctly above the receptacle. Different developmental pathw ays result in similar mature morphologies of the carpel in Persoonia f alcata and Placospermum coriaceum. Bellendena montana is unique relati ve to the other taxa in having free stamens, a punctate stigma, reduce d (not lost) floral bracts, and the floral and bract primordia are ini tiated from a common meristem. This study provides a foundation for fu ture studies of the developmental basis of floral diversity within Pro teaceae.