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)

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Angiosperm Gametophytes Evolution advantages of

•  Flowers

•  Fruits

Why so many angiosperms? •  Hypothesis – coevolution with pollinators plant-pollinator coevolution