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 Flower 1. 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 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

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 Vectors Wind Pollination: Dull, scentless flowers with reduced petals Bees/Butterfly Pollination: Bright color, nectaries, scent. They sip nectar, get pollen on coats, transfer pollen from flower to flower Bird Pollination: Nectaries, bright colors, tube-like flowers Moth Pollination: White petals, open at night Fly Pollination:Rank odor, flesh colored 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.

Ovary Each 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 roll ex. acorns Water Dispersal - Plants near water create floating fruits ex. coconuts