Plant Reproduction

Asexual and Sexual(yes, sexual!)

Asexual Reproduction

Most plants reproduce asexually Does not require fertilization

faster and requires less energy Results in clones of the parent plant

genetically identical

Vegetative propagation – a type of asexual reproduction in which new plants grow from nonreproductive plant parts

Vegetative Propagation

Stolons – runners from the stems of parent plant produce buds which grow into new plants

crabgrass, aspen trees, strawberries

Vegetative Propagation

Rhizomes – specialized stems that grow underground bamboo and sumac trees

Sexual Reproduction

Usually requires two parent plants Generates diversity in offspring Flowers – reproductive structures in angiosperms

Flower Anatomy

Flower parts are arranged in 4 concentric whorls

1. Sepals – protect flower from damage when it is a bud

2. Petals – attract pollinators often very colorful

Flower Anatomy

3. Stamens – male structure that produces pollen Anther – tip of stamen

meiosis produces spores

develop into pollen grains (contain sperm cells)

Filament – supports anther

Flower Anatomy

4. Pistil – female structure that produces ovules Stigma – sticky tip that

receives pollen Style – narrow structure

that leads pollen to ovary

Ovary – develops into fruit and produces eggs in ovules ovules develop into

seeds

Flower Anatomy

Flowers may or may not have all four of the basic flower parts Complete – has all four flower parts Incomplete – lacks any one of the four parts

“Perfect” flowers – has both stamens (male) and pistils (female) “Imperfect” flowers – lack either stamens or pistils

Sexual Reproduction

Steps in Sexual Reproduction1. Maturation of ovules2. Pollination3. Fertilization4. Seed germination

Pollination

Pollen is transferred from an anther to a stigma

Pollination

Pollen can be carried by: Wind Water Insects Birds Bats

Fertilization

Fertilization – When the sperm and egg unite. Occurs inside the ovule. The zygote develops into the embryo.

Another sperm fertilizes polar nuclei to form endosperm (food storage)

Germination

Germination – A plant emerges from the seed and begins to grow

Germination

Conditions necessary for seed germination Proper temperature Water

Steps in Seed Germination1. Seed absorbs water and swells2. Primary root develops3. Shoot begins to grow4. Cotyledons begin to shrivel

Review

1. Pollen develops2. Pollination occurs3. Upon pollination, stigma sends out pollen tube that grows through the

style to the ovary4. Sperm enters ovule (contains egg) – site of fertilization5. One sperm fertilizes egg and forms zygote6. Another sperm fertilizes polar nuclei to form endosperm (food storage)7. Zygote becomes plant embryo8. Ovule becomes seed9. Ovary develops into fruit that surrounds seed

Click here for BrainPop Pollination Animation