darwin called the evolution of the angiosperms a “ perplexing phenomenon”
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Darwin called the evolution of the Angiosperms a “ Perplexing phenomenon” …and in a letter to Joseph Hooker he called them an…. “Abominable Mystery” —Charles Darwin in a letter to Sir Joseph Hooker, 1879. Three Main Questions 1. Where did they come from? - PowerPoint PPT PresentationTRANSCRIPT
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Darwin called the evolution of the Angiosperms a
“ Perplexing phenomenon”
…and in a letter to Joseph Hooker he called them an…
![Page 4: Darwin called the evolution of the Angiosperms a “ Perplexing phenomenon”](https://reader035.vdocuments.net/reader035/viewer/2022070408/568143e2550346895db06b80/html5/thumbnails/4.jpg)
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www.jdhooker.org.uk
“Abominable Mystery”
—Charles Darwin in a letter to Sir Joseph Hooker, 1879.
Three Main Questions
1. Where did they come from?
2. How did they diversify so quickly?
3. How do they maintain high diversity?
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Stamen series from leaf-like to a slender filament.
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Lilium philadelphicum, Wood Lily, Liliaceae
Anthers with rust colored pollen
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Narcissus pollen is typical monocot pollen (monosulcate)
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Arabidopsis pollen is tricolpate (three long grooves) and is typical for a large number of dicots.
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Helianthus (Asteraceae) pollen remf.dartmouth.edu/images/botanicalPollenSEM/image/10asteraceae(helian.)pollen.jpg&imgrefurl=http://remf.dartmouth.edu/images/botanicalPollenSEM
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Ambrosia - Ragweed! Pollen
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Oak Pollen- wind dispersed
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Impatiens pollen is tetracolpate (with 4 slits). Note sculpting of exine, slits for pollen germination, and raphide crystals.
Cathy Small ‘09
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Impatiens pallida
Sepal modified to be a nectar producing spur
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Pollen
Raphide Crystals
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Rhingia naisica eating pollen of Impatiens pallida
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Pollen Tube
Stigmatic papillae
Pollen Grain -polyporate (with many round pores)
Sagina nodosa (Caryophyllaceae)
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Pollen grains germinate to form the male gametophyte
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Meiosis, 3 products Disintegrate leaving one megaspore
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1st mitotic division
2nd mitotic Division
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All megaspore images from: http://images.google.com/imgres?imgurl=www.botany.hawaii.edu/faculty/webb/BOT410/Angiosperm
3rd Mitotic Division
FemaleGametophyte (embryo sac)
Polar Nuclei