Plant Reproduction

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

Accessory Structures The calyx consists of all the sepals, which protects the flower before it opens The corolla consists of all the petals, which serve to attract pollinators through color and scent

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

Fertilization After pollen lands on stigma, a pollen tube grows down through the style to ovary Tube contains two sperm nuclei In ovary, there is one egg or ovule nucleus and two polar nuclei Double fertilization occurs: one sperm nucleus fertilizes the egg, the other the two polar nuclei

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.

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

Monocot Seed Germination Monocots grow straight up with coleoptile sheath covering shoot One embryonic leaf Seed remains underground

Dicot Seed Germination Curved stem comes up out of soil Two embryonic leaves Seed goes above soil

Parts of the Embryo Epicotyl - Grows into the leaves of the plant Hypocotyl - Becomes the stem Radicle - Becomes the root