Plant Form and FunctionAngiosperm Reproduction and

BiotechnologyPlant biology, perhaps the oldest branch of science, is driven by a combination of curiosity and needcuriosity about how plants work need to apply this knowledge judiciously to feed, clothe, and house a burgeoning human population.

Plant ReproductionAlternation of Generations

Sporophyte (diploid)• produces haploid

spores via meiosis

Gametophyte (haploid)• produce haploid

gametes via mitosis

Fertilization• joins two gametes

to form a zygote

Angiosperms Monocots and

Dicots• named for the number of

cotyledons present on the embryo of the plant

• Monocots Orchids Palms Lilies Grasses

• Dicots Roses Beans Sunflowers Oaks

Angiosperm Life Cycle Sporophyte (diploid)

• actual plant with flowers

Gametophyte (haploid)• male: germinated

pollen grain• female: embryo

sac

Fertilization• joins two gametes

to form a zygote

Moss Life Cycle Gametophyte

• dominant generation• has both sexes and

produces gametes archegonia (eggs) antheridia (sperm)

Fertilization• sperm move along moss to

find archegonia

Sporophyte• grows on top of gametophyte • sporangia is where spores

are produced by meiosis

Fern Life Cycle Sporophyte

• produce spores via meiosis

• spores develop into young gametophyte

Gametophyte• has both sexes and

produces gametes archegonia (eggs) antheridia (sperm)

Fertilization• similar to mosses

Gymnosperm Life Cycle Sporophyte

• produce gametophytes inside of cones

• Pollen cone (male) produces microspore

via meiosis• Ovulate cone (female)

produces megaspores via meiosis

Fertilization• pollen grains discharge

sperm into egg

Male and Female Gametophyte of Flowering Plant

Male Gametophyte• pollen grain

microspores produced within the anther

divide once to produce two sperm cells

FemaleGametophye• embryo sac

megaspore produced within the ovule

divide to produce three egg cells and 2 polar nuclei

Double Fertilization Pollen grain lands on stigma

Pollen tube toward ovule

Both sperm discharged down the tube

Egg and one of the sperm produce zygote

2 polar nuclei and sperm cell produce endosperm

Ovule becomes the seed coat

Ovary becomes the fruit

Seed Structure and Development

Mechanisms That Prevent Self-Fertilization

The most common anti-selfing mechanism in flowering plant is known as self-incompatibility, the ability of a plant to reject its own pollen

Stigma

Antherwith

pollen

Stigma

Pin flower Thrum flower

Emerging Plant The radicle is the

first organ to emerge from the germinating seed

In many eudicots a hook forms in the hypocotyl, and growth pushes the hook above ground

Foliage leaves

Cotyledon

Hypocotyl

Radicle

Epicotyl

Seed coat

Cotyledon

Hypocotyl Cotyledon

Hypocotyl

Emerging Plant Monocots use a

different method for breaking ground when they germinate

The coleoptile Pushes upward through the soil and into the air

Foliage leaves

ColeoptileColeoptile

Radicle