Book contents
- Frontmatter
- Contents
- Foreword
- Preface
- Acknowledgments
- Part I Introduction to floral diagrams
- Part II Floral diagrams in the major clades
- 4 Systematic significance of floral diagrams
- 5 Basal angiosperms: the ascent of flowers
- 6 Monocots: variation on a trimerous Bauplan
- 7 Early diverging eudicots: a transition between two worlds
- 8 Basal core eudicots: the event of pentamerous flowers
- 9 Caryophyllids: how to reinvent lost petals
- 10 Rosids: the diplostemonous alliance
- 11 Asterids: tubes and pseudanthia
- Part III Conclusions
- References
- Glossary
- Taxonomic index
- Subject index
5 - Basal angiosperms: the ascent of flowers
Published online by Cambridge University Press: 24 January 2011
- Frontmatter
- Contents
- Foreword
- Preface
- Acknowledgments
- Part I Introduction to floral diagrams
- Part II Floral diagrams in the major clades
- 4 Systematic significance of floral diagrams
- 5 Basal angiosperms: the ascent of flowers
- 6 Monocots: variation on a trimerous Bauplan
- 7 Early diverging eudicots: a transition between two worlds
- 8 Basal core eudicots: the event of pentamerous flowers
- 9 Caryophyllids: how to reinvent lost petals
- 10 Rosids: the diplostemonous alliance
- 11 Asterids: tubes and pseudanthia
- Part III Conclusions
- References
- Glossary
- Taxonomic index
- Subject index
Summary
The basal angiosperms are a grade comprising the main part of Magnoliidae sensu Cronquist (1981) minus Ranunculales, which belong to the basal eudicots. The monocots are nested within the basal Angiosperms. Figure 5.1 summarizes the phylogenetic relationships of the main families and orders according to Soltis et al. (2005). The position of Chloranthaceae and Ceratophyllaceae is debatable according to recent phylogenies, depending on emphasis on molecular or morphological analyses (see e.g. Moore et al., 1997; Jansen et al., 2007; Endress and Doyle, 2009).
The ANA-grade: Amborellales, Austrobaileyales, Nymphaeales
The ANA-grade (formerly ANITA-grade: Qui et al., 1999) groups the basalmost lineages of the Angiosperms. Among these taxa the monotypic Amborella trichopoda has recently been identified on molecular evidence as the basalmost extant angiosperm (Soltis et al., 2005; Jansen et al., 2007). Since then, morphological studies have confirmed the basal nature of these early-diverging lineages (see e.g. Endress, 2001; Ronse De Craene, Soltis and Soltis, 2003; Buzgo, Soltis and Soltis, 2004; Endress and Doyle, 2009). Most taxa of the ANA-grade share spiral (or whorled) flowers with a morphological continuum between bracts and perianth, indefinite number of organs and a central receptacular residue. However, perianth initiation and differentiation is variable in the grade. Endress (2008c) argued that a multistep gradation from bracts to inner tepals may be secondary, as this is absent from Amborella. Some characters appear derived and have evolved independently, such as unisexual flowers and adaptations to specific pollinators.
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- Information
- Floral DiagramsAn Aid to Understanding Flower Morphology and Evolution, pp. 63 - 87Publisher: Cambridge University PressPrint publication year: 2010