Date of Award
Doctor of Philosophy (PhD)
Shirley C. Tucker
Comparative floral and inflorescence ontogenies among Proteaceae are examined and a phylogenetic analysis based on principles of parsimony is presented. Comparative developmental and morphological investigations indicate that the fourmerous flowers are primitively simple. Each flower is composed of: a single series of four tepals that are initiated in two dimerous whorls (in most taxa); four stamens, each one initiated opposite a tepal and generally fused to the tepal at various heights due to zonal growth; and a single carpel. Ontogenetic studies reveal that the nectaries arise late in development and are not homologous to a reduced petal or stamen whorl. The inflorescences of Proteaceae are racemose. Inflorescences among Grevilleoideae are more complex. The flower pairs of Grevilleoideae represent two flowers on a short-shoot; each flower is usually subtended by a floral bract, and the flowers are dorsiventral, with two tepals in both the median sagittal plane and the median frontal plane, like flowers in the other four subfamilies. The origin of the two-flowered short-shoots is either a result of reduction of secondary inflorescence branches or the product of an amplification event of first-order meristems along a primary axis. There are two forms of carpel initiation among taxa: a terminal transformation of the floral apex after stamen initiation, present in most taxa; in other taxa, the carpel is intiated in a lateral position and an apical residuum persists. Among grevilleoidean taxa, there are six orientations of the carpel conserved at different taxonomic levels. Developmental and morphological data are utilized in a phylogenetic analysis of 53 proteaceous taxa. Ontogenetic comparisons provide a clarified interpretation of floral diversity among taxa as well as a fundamental understanding of homology among characters in diverse taxa. The ontogenetic comparisons provided additional characters based on their timing and presence in the developmental program. The 154 characters provide a well resolved phylogeny of the family. The phylogenetic evidence does not support the currently accepted classification of the family, as Persoonioideae and Proteoideae are not monophyletic and 14 of 17 tribes and 4 of 25 subtribes examined within the family are also nonmonophyletic.
Douglas, Andrew William, "Evolutionary Patterns in Proteaceae Based on Comparative Floral and Inflorescence Ontogenies." (1994). LSU Historical Dissertations and Theses. 5868.