4/4/19
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Flowering Plants
• Show and Tell – Fossil plants!!
• Finish Gymnosperms – Life cycle
• Characteristics of Flowering Plants – Angiosperm Life Cycle – Plant Sex
• Why so many species of Flowering Plants?
April 5, 2019
Ovule
Mature sporophyte (2n) MEIOSIS
Megasporangium (2n)
Microsporangium (2n)
Archegonium Female gametophyte
Seeds
Sperm (n) Pollen tube
Egg (n) Haploid (n) Diploid (2n)
Embryo (new sporophyte) (2n)
Pollen (n)
MEIOSIS
FERTILIZATION
The Life Cycle of a Pine Tree
Pollen and Seed Cones of a Pine
Seed cones
pollen cones
Gymnosperms – unprotected seeds
Cycads Ginkgo (1 sp)
Gnetophytes Conifers
Dominant in mesozoic. <1000 living spp
(but still abundant)
Angiosperms – the flowering plants
Stamen Anther
Filament
Stigma Carpel
Style
Ovary
Petal
Sepal
Ovule Male and female gametes in same structure – the flower
4/4/19
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(a) Archaefructus sinensis, a 125- million-year-old fossil
(b) Artist’s reconstruction of Archaefructus sinensis
Carpel
Stamen
5 cm
Figure 30.11
Carpels and Stamens Evolved from Leaflike Structures
Flowering plants diversified recently
ßTertiary
ß Origin of flowering plants
>250,000 species of angiosperms!
Seeds retained in modified ovary à fruit
Anther
Mature flower on sporophyte plant (2n) Ovary
Embryo (2n) Endosperm (3n)
Seed coat (2n)
Female Gametophyte (in ovule)
Egg cell (n)
Style
Sperm Pollen tube Stigma
Microspore (n)
Male gametophyte (in pollen grain)
Ovule (2n)
MEIOSIS
MEIOSIS
FERTILIZATION
Key Haploid (n) Diploid (2n)
4/4/19
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Angiosperm Gametophytes Evolution advantages of
• Flowers
• Fruits
Why so many angiosperms? • Hypothesis – coevolution with pollinators plant-pollinator coevolution