Publication Date
8-23-1991
Series Number
208
Abstract
Angiosperm ovules and carpels have numerous characters and character states, not all of which have been utilized in phylogenetic analyses. A character analysis of these two organs is performed, including description of characters and states, and character polarization to identify the ancestral states. In addition, the distributions of these states are examined in the Magnoliidae and putatively basal orders of Hamamelidae, Caryophyllidae, Dilleniidae, Rosidae, Alismatidae (sensu Cronquist 1981), and Liliiflorae (sensu Dahlgren et al. 1985). These support two hypotheses: the ancestral ovules were orthotropous, bitegmic and crassinucellar, based on current terminology; and ancestral carpels had ascidate morphology and one or two ovules. Separate structural hypotheses for the evolution of ovules and of carpels are interpreted and indicate that anatropous ovules and plicate (conduplicate) carpels are derived. Finally, these analyses suggest that since the dicots Chloranthaceae, Saururaceae, Piperaceae and Amborellaceae and the monocots Dioscoreales (e.g., Stemonaceae and Smitacaceae) have all the suggested ancestral states, they may be most similar to the morphology of the ancestral angiosperm.