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: Vfo62Lghttp:// Vfo62Lg Fern life cycle: Y0duNjghttp:// 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:

Plant Reproduction Song TNRU0http:// TNRU0

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 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 - Plants near water create floating fruits ex. coconuts