Flower Morphology and Flower Morphology and DevelopmentDevelopment
OverviewOverviewFloral MorphologyFloral Morphology
Flower PartsFlower Parts
Flower DevelopmentFlower Development
Floral EvolutionFloral EvolutionPaleoherbsPaleoherbs
Evolved in dry upland Evolved in dry upland habitats (habitats (AxelrodAxelrod).).Supported by Supported by paleopaleobotanists.botanists.
Woody magnoliasWoody magnoliasTropical shrubs.Tropical shrubs.Not diversified in Not diversified in contemporary florascontemporary florasSupported by Supported by molecular analyses of molecular analyses of living living taxataxa (Doyle and (Doyle and DonoghueDonoghue). ).
Floral EvolutionFloral Evolution
Evolutionary TrendsEvolutionary Trends
Ovules enclosedOvules enclosedOvules exposedOvules exposed
DerivedDerived(advanced)(advanced)
AncestralAncestral(primitive)(primitive)
Few (invariable)Few (invariable)flower partsflower parts
Multiple (variable) Multiple (variable) flower partsflower parts
Bilateral Bilateral symmetrysymmetryZygomorphicZygomorphic
Radial symmetryRadial symmetryActinomorphicActinomorphic
Ovary inferiorOvary inferiorOvary superiorOvary superior
Parts within a Parts within a whorl fusedwhorl fused
Parts within a Parts within a whorl separatewhorl separate
A
B
C
D
EPhylogenetic Tree(cladogram)
Evolution of AngiospermsEvolution of AngiospermsBryophyte fossils back to 425 Bryophyte fossils back to 425 MYBP.MYBP.First Angiosperm fossil records First Angiosperm fossil records 130 MYBP during the Jurassic.130 MYBP during the Jurassic.
Perhaps as early as 250 MYBP Perhaps as early as 250 MYBP based on chemical evidence.based on chemical evidence.
Began to spread and become Began to spread and become dominant during the dominant during the CretaceousCretaceous
Association with animals.Association with animals.250,000 species in 350 250,000 species in 350 families.families.Molecular and morphological Molecular and morphological characters indicate characters indicate monophyletic origin.monophyletic origin.Initial origin and spread in Initial origin and spread in Gondwanaland. Gondwanaland.
500 MYBP
Floral MorphologyFloral MorphologyThe concept of floral The concept of floral syndromes.syndromes.
MorphologyMorphologyColorColorScentScentNectar compositionNectar compositionPhenologyPhenology
Floral MorphologyFloral Morphology
The concept of specialization.The concept of specialization.Phenotypic attributes that Phenotypic attributes that promote the association with a promote the association with a single pollinator species, or a single pollinator species, or a guild of pollinators.guild of pollinators.PhylogeneticPhylogenetic trends.trends.
PolyphilyPolyphily (generalists)(generalists)OligophilyOligophily (specialists)(specialists)Example: Example: RanunculaceaeRanunculaceae(buttercup family)(buttercup family)
Floral SpecializationFloral SpecializationTrends towards Trends towards specializationspecialization::
SymmetrySymmetryRadial (Radial (actinomorphicactinomorphic))
Cup, bell, or brushCup, bell, or brush--shaped flowersshaped flowersBilateral (Bilateral (zygomorphiczygomorphic))
Peas, orchids, mints, irises, etc.Peas, orchids, mints, irises, etc.
PerianthPerianthOpenOpenTubularTubular
RewardReward--access mechanismsaccess mechanismsReward typeReward type
Floral tissue/pollenFloral tissue/pollenNectarNectarNonNon--nectar reward typesnectar reward types
Floral MorphologyFloral Morphology
PerianthPerianth colorcolorTriTri--chromatic vision of insects.chromatic vision of insects.
Shifted to UV, red “blind.”Shifted to UV, red “blind.”
Color by pollinator.Color by pollinator.Bees Bees –– yellow, blue.yellow, blue.Butterflies Butterflies –– yellow, blue.yellow, blue.Moths Moths –– white, yellow.white, yellow.Hummingbirds Hummingbirds –– red, yellow.red, yellow.
Floral MorphologyFloral Morphology
PerianthPerianth color color patternspatterns
Bee pollinationBee pollinationTargetsTargetsNectar guides.Nectar guides.
Pollination SyndromesPollination Syndromes
ScentScentBees use scent profiles to locate flowersBees use scent profiles to locate flowersMoth pollination Moth pollination –– often sweet smellingoften sweet smellingFly/beetle pollination Fly/beetle pollination –– rancid scentsrancid scents
NectarNectarSugar concentration (10 Sugar concentration (10 –– 74%)74%)Sugar composition (Baker and Baker, Sugar composition (Baker and Baker, 1979)1979)
Sucrose/Sucrose/HexoseHexose (glucose, fructose) ratio.(glucose, fructose) ratio.Amino acids.Amino acids.
PhenologyPhenologyFlower longevityFlower longevityNightNight--blooming speciesblooming species
Floral Syndromes Floral Syndromes –– Current ViewsCurrent Views
Pollinator specialization Pollinator specialization -- coevolutioncoevolutionFaegri and van der Pijl, 1979
Syndromes are “generalized”Syndromes are “generalized”WaserWaser et al., 1996et al., 1996
Challenge to the pollinator effectiveness Challenge to the pollinator effectiveness hypothesis.hypothesis.
NonNon--coevolved pollinators (bees) deposit more pollen coevolved pollinators (bees) deposit more pollen in in IpomopsisIpomopsis Mayfield et al., 2001Mayfield et al., 2001FensterFenster et al. 2004.et al. 2004.
Floral Syndromes Floral Syndromes –– Current ViewsCurrent Views
Hypotheses for the evolution of Hypotheses for the evolution of syndromessyndromes
Pollinator effectivenessPollinator effectivenessInducing pollinator constancyInducing pollinator constancyExcluding unwanted pollinatorsExcluding unwanted pollinators
Current ResearchCurrent Research
Tim Holtsford labhttp://www.biosci.missouri.edu/holtsford/nicotiana/
Scott Hodges labhttp://www.lifesci.ucsb.edu/eemb/faculty/hodges/research.html
BibliographyBibliography
Baker, H. G., and I. Baker. 1979. Sugar ratios in nectars. Phytochemical Bulletin 12:43-45.Faegri, K., and L. van der Pijl. 1979. The Principles of Pollination Ecology. Pergamon, Oxford.Hodges, S. A., and M. L. Arnold. 1994. Columbines: a geographically widespread species flock. Proc-Natl-Acad-Sci-U-S-A. 91:5129-5132.Mayfield, M. M., N. M. Waser, and M. V. Price. 2001. Exploring the 'most effective pollinator principle' with complex flowers: Bumblebees and Ipomopsis aggregata. Annals of Botany 88:591-596.Waser, N. M., L. Chittka, M. V. Price, N. M. Williams, and J. Ollerton. 1996. Generalization in pollination systems, and why it matters.Ecology 77:1043-1060.