Basic Flower Structure

stigma

style

ovary

locule

ovule

carpelgynoecium

pollen

anther

filament stamenandroecium

petal

corolla

perianthsepalcalyx

receptacle

pedicelPerianth is complete

Flower is perfectFlower is monoecious

superior

Flower is hypogynous

Pistil is simple

This longitudinal section view does not allow us to consider symmetry

pollen dehiscence

pollination

pollen tube growth

chemotropismsyngamyx

vectors: animals, wind

Flower Functions Leading to Sex

What are the rest of the flower parts doing?

Anther Cross Section - How many anther sacs are present?

epidermis

vein

mesophyll

pollen grains

Pollen grainTube Cell Generative

Cellcytoplasm

nucleus

nucleolus

cytoplasm

nucleus

nucleolus

Pollen Wall

Digests path through stigma, style, and ovary.Locates micropyle of ovule.Penetrates into embryo sac.

Divides by mitosis to make two sperm.Both join in syngamy events.

Waterproofing prevents desiccation during pollen transfer. Recognition proteins cause allergic reactions.

Pollen Grain

Pollen Wall

Generative Cell

TubeCell

Cytoplasm

Nucleus

Nucleolus

Cytoplasm

Nucleus

Nucleolus

Fate:Digests Path to EggLocates MicropyleEnters Embryo SacIs Burst to Release Sperm

Fate:Follows Path of Tube

Divides by MitosisMakes Two Sperm

Both Have Syngamy

Pollen grain deposited by vector on stigma

Tube cell germinates through pollen wall

Pollen tube digests pathway to eggAttracted to source of hormones, Calcium, BoronChemotropism toward micropyle of ovulePenetrates into embryo sac

Generative cell divides to make two sperm cells.

tube nucleus tube

nucleus

generative nucleus

pollen tube

Golgiandvesicles

Synergids burst end of pollen tube.Sperm released into embryo sac.Syngamy events follow.

Generative cell follows pathway of pollen tube.

Rhododendron maximum ovule ls

Embryo Sac

disintegrate

+ sperm = endosperm

+ sperm = zygote

burst pollen tuberelease spermdisintegrate

Micropyle of Integument

2 Synergid Cells

Egg Cell

Central Cell

3 Antipodal Cells

Integument

Embryo Sac in Ovule

OvuleEmbryo

Sac

Antipodals

Central Cell

Egg

Synergids

Integument

Funiculus

Micropyle

Plant Pornography?

Central Cell

Egg Cell

Syngamy Product = Endosperm 3N

Syngamy Product = Zygote 2N

Disintegrating Antipodals

Sperm Nucleus

Polar Nuclei

Sperm Nucleus

Egg Nucleus

Disintegrating Synergids

After Syngamy, the Names are Changed…

• Egg becomes Zygote

• Central cell becomes Endosperm

• Ovule becomes Seed

• Integument becomes Seed coat

• Ovary wall becomes Fruit

Capsella shepherd’s purse seed

Integument became seed coat

Egg became zygoteZygote became embryo

Central Cell became endosperm

Ovary became fruit