Flowering Plants, Evolution

Abstract

The evolution of angiosperms shows a tendency to an increase in canalization and synorganization, but it is also characterized by widespread parallelism and reversal. The great diversity shown by extant angiosperms is concentrated in a relatively few clades.

Keywords: diversification; speciation; parallelism; canalization; synorganization; uncertainty

Figure 1.

Conservative phylogeny of major angiosperm clades.

Figure 2.

ANITA grade‐Nymphaeales‐Nymphaeaceae. Nymphaea odorata. (a) habit, rhizomatous, with peltate leaves (apomorphies associated with aquatic habitat); (b) flower with large, variable numbers of spirally arranged parts; (c–h) transition series from petals to stamens; (i) inferior ovary (apomorphy) with spiral arrangement of parts removed; style short, stigmatic surface large; (j) single carpel; (k) seed; (l) seed (l.s.) with small embryo and much perisperm.

Figure 3.

Monocots‐Asparagales‐Asparagaceae s.l. (a–e) Maianthemum racemosum, (f,g) M. canadense (a) habit, rhizomatous habit, terminal inflorescence, parallel venation, absence of tap root; (b) flower, parts in threes; (c) ovary (t.s.), arrow points to position of septal nectary; (d) baccate fruit; (e) rather stubby embryo; (f) 2‐merous flowers unusual in monocots, but stamens opposite each tepal member is common; (g) rhizomatous habit.

Figure 4.

Eudicots‐Ranunculales‐Ranunculaceae. Caltha palustris. (a) habit; (b) flower with a single whorl of tepals and free carpels; numerous stamens are probably an apomorphy of Ranunculaceae; (c) stamen, anther and filament not sharply distinguished; (d) carpel, style short, stigma decurrent, nectaries at base of carpel; (e) fruit a follicle, opening adaxially; (f) seed (l.s.), very small embryo embedded in copious endosperm.

Figure 5.

Euasterid II ‐Dipsacales‐Caprifoliaceae. (a–c, e–f) Lonicera sempervirens; (d) L. japonica. (a) habit, opposite leaves constant in order, leaves fused at base notably common; (b) old inflorescence, basic construction cymose (common in euasterids), small, narrow calyx common in order; (c) tubular corolla, common in asterids; (d) corolla opened, stamens attached to petals; (e) tricarpellate gynoecium (common in euasterid II group); (f) weakly monosymmetric flower; (g) embryo.

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Further Reading

Angiosperm Phylogeny Group (2003) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399–436.

Doyle JA (2001) Significance of molecular phylogenetic analyses for paleobotanical investigations on the origin of angiosperms. Paleobotanist 50: 167–188.

Endress PK (1994) Diversity and Evolutionary Biology of Tropical Flowers. Cambridge: Cambridge University Press.

Endress PK (2001) Evolution of floral symmetry. Current Opinion in Plant Biology 4: 86–91.

Judd WS, Campbell CS, Kellogg EA, Stevens PF and Donoghue MJ (2002) Plant Systematics: A Phylogenetic Approach, 2nd edn. Sunderland, MA: Sinauer.

Mabberley DJ (1997) The Plant‐Book. Cambridge: Cambridge University Press.

Magallon S and Sanderson MJ (2001) Absolute diversification rates in angiosperm clades. Evolution 55: 1762–1780.

Sotis DE, Sotis PS, Endress PK and Chase MW (2005) Phylogeny and Evolution of Angiosperms. Sunderland, MA: Sinauer.

Stevens PF (2001 onwards) http://www.mobot.org/MOBOT/research/APweb/welcome.html

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How to Cite close
Stevens, Peter F(Jan 2006) Flowering Plants, Evolution. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003361]