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. List some benefits and some drawbacks to asexual reproduction. Fast, no mate required. Beneficial for plants that must compete for scarce resources. However, all individuals are genetically identical.

Sexual Reproduction Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule. List some advantages and drawbacks to sexual reproduction. Fusion of egg and sperm cells. May be limited to a certain season. Slower than asexual reproduction. Allows genetic mixing, increasing variability in a population.

Terms to know: Haploid: having a single set of chromosomes in each cell. Diploid: having two sets of chromosomes in each cell. Mitosis: cell division, which produces two genetically identical cells. Meiosis: reduction division, which produces four haploid reproductive cells.

Animals vs. Plants Plant Reproduction Animal Reproduction Life cycle Alternation of generations No alternation of generations Gametes Haploid gametes Spores Haploid spores No spores Gametes made by Haploid gametophyte, by mitosis Diploid organism, by meiosis Spores made by Diploid sporophyte, by meiosis

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? What kinds of limits does external reproduction impose on these plants? Reproduction in these plants requires wet conditions, and requires having male and female parts close together. Living conditions, plant size, and genetic mixing is limited.

Flowers

Flower Parts

Basic Flower Structure stigma carpel gynoecium locule Flower is perfect Flower is monoecious style pollen ovule ovary anther filament stamen androecium petal corolla sepal perianth receptacle calyx Perianth is complete pedicel

Some Example Stories: Perfect Flowers: Pea exclusively self-pollinating Hibiscus self-pollinating if not crossed Cherry self-incompatible only outcrosses Imperfect Flowers: Begonia unisexual but monoecious Holly unisexual and dioecious Variable: Cucumber male, perfect, female, parthenocarpic

Basic Flower Structure stigma carpel Pistil is simple gynoecium locule Flower is perfect Flower is monoecious style pollen ovule ovary anther superior filament stamen Flower is hypogynous androecium petal corolla sepal perianth receptacle calyx Perianth is complete pedicel

Ovary Superior Flower Hypogynous Ovary Half-Superior Flower Perigynous Ovary Half-Inferior Flower Epigynous Ovary Inferior

Basic Flower Structure stigma carpel Pistil is simple gynoecium locule Flower is perfect Flower is monoecious style pollen ovule ovary anther superior filament stamen Flower is hypogynous androecium petal corolla sepal perianth receptacle calyx Perianth is complete pedicel This longitudinal section view does not allow us to consider symmetry

Flower Formula: Symbol Sequence to Diagram Flower * 5, 5, , 5 * 5, Symmetry: *=radial †=bilateral * 5, 5, , 5 * 5, * 5, 5, * 5, 5, , * Number of Parts per Whorl: sepals in calyx petals in corolla stamens in androecium carpels in gynoecium Fusion within whorl: curved line over number Fusion between whorls: square bracket below numbers Attachment of flower parts relative to ovary: horizontal line

1 1 1 Ovary Superior Flower Hypogynous Ovary Half-Superior Flower Perigynous 1 Ovary Half-Inferior Flower Epigynous Ovary Inferior 1

Incomplete flowers Flowers are complete if they have all parts, and perfect if they have both male and female parts. Grass flowers: incomplete, usually imperfect (separate male and female flowers) A tulip is complete (though the sepals are the same color as the petals) and perfect.

Gametogenesis: Male

Gametogenesis: Female

Double Fertilization

Flower to Fruit

Ovule to Seed

Seed Anatomy

Seed Germination