Plant Reproduction Angiosperms flowering plants Plants that protect

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 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 2 n (diploid) embryo {The other sperm nucleus and the two polar nuclei join to form a 3 n (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