Bellringer-April 1, 2014 How do flowers reproduce? Do flowers have separate male and female organs? How do flowers pollinate? Provide examples.

Flowers/Reproduction Honors Biology

Plant Life Cycle Plant life cycles alternate between a sporophyte phase, which produces spores, and a gametophyte stage, which produces gametes. A zygote divides by mitosis and grows into a mature sporophyte, or spore-producing plant. A spore divides by mitosis and grows into a mature gametophyte, or gamete-producing plant.

Flowering Plant Reproduction Pollen grains Ovule Flower Meiosis Mitosis Flowers are modified leaves, specialized for reproduction (where pollination takes place). Flower parts undergo meiosis to produce haploid products pollen grain ovule (contains egg cell)

Flower Sexual reproductive structure Produces egg and sperm Fertilization takes place inside the flower Reproduces sexually (cross-pollination) and asexually (self-pollination).

The flower: the defining structure of angiosperms Reproductive structure: pollen transfer; specialized shoot with modified leaves Sepals: enclose flower before it opens Petals: attract pollinators Stamens: male sex organs; anther (produces pollen), filament Carpels (Pistil): female sex organs; stigma, style, ovary, ovules

*Stigma –top of the pistil, Sticky surface for pollen to stick to Female reproductive organ Male reproductive organ Pistil *Stigma –top of the pistil, Sticky surface for pollen to stick to *Style – connects the stigma to the ovary *Ovary –contains ovules ( eggs) Stamen *Anther – produces sperm nuclei by meiosis. Sperm nuclei are enclosed by pollen grains. *Filament – holds the anther up

Pollination Flowers/fruits can be carried by wind, water, or animals to new locations, enhancing seed dispersal Wings enable maple fruits to be easily carried by the wind. (a) Seeds within berries and other edible fruits are often dispersed in animal feces. (b) The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals. (c) Figure 30.9a–c

Pollination: Transfer of mature pollen grains from the anther to the stigma

When a pollen grain lands on the stigma, it germinates and a pollen tube grows down through the style to an ovule (egg)

Fertilization The sperm travels through the pollen tube to the ovule. The sperm & egg fuse forming the zygote (fertilized egg) –this grows into the plant embryo (cells grow by mitosis)

Self pollination –pollen from same flower *Self pollination –pollen from same flower *Cross pollination – pollen from a different flower - more variation

Pollination is the transfer of pollen from the anther to the stigma Click to view the animation This is an example of cross-pollination as the pollen travels from one flower to a different flower. This is desirable in plants as it promotes variation. Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Self-pollination occurs when pollen falls from the anther onto the stigma of the same flower Click to show animation of self-pollination Self-pollination is not desirable as it reduces variation Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Flowers will prevent self-pollination by either having stigma above stamen or… Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

…by having stamen and stigma mature at different times. Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

The ovary and zygote (fertilized ovule) develop and ripen. *The ovule forms the seed and the ovary forms the fruit. Seed = embryo + stored food + seed coat Fruit = ovary wall, mechanism for seed dispersal A fruit is a ripened ovary

Fruits Form when ovary with ovules (eggs) ripens May be dry and hardened (nuts) May be enlarged and fleshy (berries, apples, tomatoes) …TASTY!!! Used to help disperse seeds

Flowers, Fruits, and vegetables A fruit is the part of the plant that develops from a flower. It's also the section of the plant that contains the seeds. (Protects the seeds). The other parts of plants are considered vegetables. These include the stems, leaves and roots — and even the flower bud.

Dead Center sits the tomato. Why?

Dead Center sits the tomato. Why? Botanically speaking, a tomato is a fruit because it is a seed-bearing structure that develops from the ovary of a flowering plant. In the culinary world sweet = fruits and savory = vegetables: this includes botanical fruits as eggplants, bell peppers, and tomatoes.