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? 2. How did they diversify so quickly? 3. How do they maintain high diversity? www.jdhooker.org.uk
Anthers with rust colored pollen Lilium philadelphicum, Wood Lily, Liliaceae
Arabidopsis pollen is tricolpate (three long grooves) and is typical for a large number of dicots.
Helianthus (Asteraceae) pollenremf.dartmouth.edu/images/botanicalPollenSEM/image/10asteraceae(helian.)pollen.jpg&imgrefurl=http://remf.dartmouth.edu/images/botanicalPollenSEM
Cathy Small ‘09 Impatiens pollen is tetracolpate (with 4 slits). Note sculpting of exine, slits for pollen germination, and raphide crystals.
Sepal modified to be a nectar producing spur Impatiens pallida
Raphide Crystals Pollen
Sagina nodosa (Caryophyllaceae) Pollen Tube Stigmatic papillae Pollen Grain -polyporate (with many round pores)
3 4 2nd mitotic Division 5 Meiosis, 3 products Disintegrate leaving one megaspore 1st mitotic division
Female Gametophyte (embryo sac) Polar Nuclei 3rd Mitotic Division All megaspore images from: http://images.google.com/imgres?imgurl=www.botany.hawaii.edu/faculty/webb/BOT410/Angiosperm