Plant Reproduction

Angiosperms (flowering plants)• Plants that protect their seeds within the body

of a fruit.

• Make up ¾’s of all plants, including:

– Trees, shrubs, herbs,

grasses, water plants…

Structure of a Flower1. Pistil

2. Stigma

3. Style

4. Ovary

5. Stamen

6. Filament

7. Anther

8. Petal

9. Sepal

10. Receptacle

11. Stem

Male Reproductive Structure

The stamen consists of two parts: Anther and Filament

The anther is where meiosis occurs to produce haploid pollen

The filament is a stalk that supports the anther

Female Reproductive StructureThe pistil consists of

the stigma, style and ovary

The sticky stigma receives the pollen from the anther

The pollen grows a tube down through the style

Meiosis occurs in the ovary to produce haploid ovules

Reproductive Structures

• Petals: colourful

structures that attract pollinators.

• Sepals: surround and protect the flower bud.

Pollination

Wind, insects or other animals transfer pollen from the anther of one flower to the stigma of another

Flowers vary depending on pollination mechanism

Pollination Animation

Pollination VectorsWind Pollination: Dull, scentless flowers with reduced petalsBees/Butterfly Pollination: Brightcolor, nectaries, scent. They sip nectar, get pollen on coats, transfer pollen from flower to flower

Bird Pollination: Nectaries, brightcolors, tube-like flowers

Moth Pollination: White petals, open at night

Fly Pollination:Rank odor, fleshcolored petals

• Pollen Grain • Anther Sac

Pollen grains contain two haploid cells produced through meiosis.

1- The Tube cell – will grow the pollen tube. 2- The Generative cell – will go through mitosis to create two sperm cells.

OvaryEach ovule within an ovary has a micropyle (an opening for the pollen tube). The ovules’ megasporangium undergo meiosis to produce four haploid cells (3 die leaving 1 megaspore)The megaspore undergoes mitosis 3 times to produce 8 haploid cells within the embryo sac.

Fertilization

After pollen lands on the stigma, a pollen tube grows down through the style to ovary

Generative cell creates the two sperm nuclei Double fertilization occurs:

one sperm fertilizes the egg one sperm the two polar nuclei together

Result of Double Fertilization

The sperm nucleus and egg nucleus join to form a 2n (diploid) embryo

The other sperm nucleus and the two polar nuclei join to form a 3n (triploid) endosperm. The endosperm is the food supply for the embryo.

First link

Seed and Fruit Development After fertilization,

the petals and sepals fall off flower

Ovary “ripens” into a fruit

The ovule develops into a seed

Seed Dispersal Mechanisms-Allow plants to colonize new areas and avoid

shade of parent plant

Wind Dispersal - Flight mechanisms, like parachutes, wings, etc. Ex. Dandelion, maples, birch

Animal Dispersal - Fleshy fruits which animals eat, drop undigested seeds in feces or burrs which stick to animals’ coats

Gravity Dispersal - Heavy nuts fall to ground and rollex. acorns

Water Dispersal - Plantsnear water create floating fruitsex. coconuts