Plant Reproduction

Asexual Reproduction

• Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.

Sexual Reproduction

• Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule.

Plant Life Cycle

Alternation of Generations

• Plants have a double life cycle with two distinct forms:

• Sporophyte: diploid, produce haploid spores by meiosis.

• Gametophyte: haploid, produce gametes by mitosis.

Non-flowering plants

• Mosses, ferns, and related plants have motile, swimming sperm.

• What kind of environmental conditions would be required for reproduction in these plants?

Moss Life Cycle

Fern Life Cycle

• Moss life cycle:

• http://www.youtube.com/watch?v=o1z0Vfo62Lg

• Fern life cycle:

• http://www.youtube.com/watch?v=Fhk-Y0duNjg

Conifers

• Conifers (also non-flowering plants) have reduced gametophytes.

• Male gametophyte is contained in a dry pollen grain.

• Female gametophyte is a few cells inside of the structures that become the seed.

Conifer life cycle

Conifer pollination

• Conifers are wind-pollinated plants.

• Chance allows some pollen to land on the scales of female cones.

• Pollen germinates, grows a pollen tube into the egg to allow sperm to fertilize the egg.

• Life Cycle: http://www.youtube.com/watch?v=WPfRV8NWkk4

Plant Reproduction Song

• http://www.youtube.com/watch?v=35vPjdTNRU0

Flowers

Flower Parts

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 Structure

The 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

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

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

Angiosperm Life Cycle

Gametogenesis: Male

Gametogenesis: Female

Double Fertilization

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

Flower to Fruit

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

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 roll

ex. acorns

Water Dispersal - Plantsnear water create floating

fruitsex. coconuts