Flower Function Flowers make reproduction more efficient
A flower is the location of sexual reproduction in flowering plants
Flower Structure Sepal- part of which encloses the bud before it opens. Protects the flower Petal- colored leaves on the flower. Attracts pollinators Stamen- consists of filament and anther (male reproductive organ) Anther- structure where male reproduction occurs and pollen is made Filament- thin, stem-like stalk, supporting anther Pistil- ovary, stigma, and style (female reproductive organ) Ovary- base of pistil which holds the ovules (eggs) Stigma- upper part of pistil where pollen is deposited Style- stalk between stigma and ovary
Complete Flower Structure
Pollination Flowering plants use the wind, insects, bats, birds and mammals to transfer pollen from the male (stamen) part of the flower to the female (stigma) part of the flower A flower is pollinated when a pollen grain lands on its stigma Pollen grains germinate on the stigma, growing down the style to reach an ovule. The sperm cells enter the ovule through an opening called the micropyle
Pollination Some flowers, such as grasses, do not have brightly colored petals and nectar to attract insects. They do have stamens and pistils. These flowers are pollinated by the wind.
Fertilization Double fertilization Unique to angiosperms
Each pollen grain has two sperm cells (n) One sperm (n) fertilizes one of six egg cells(n) to form a diploid zygote (2n). The other sperm (n) fuses with the central cell (2n) to form a triploid cell (3n) This triploid cell becomes the endosperm of the seed
Seeds and Fruits Seed Formation
After fertilization most of the flower parts die and seeds develop The wall of the ovule becomes seed coat The zygote inside ovule develops into plant embryo
Seeds and Fruits Fruit Formation
The ovary enlarges and becomes the fruit The fruit contains the seeds Types of fruits Fleshy fruits– apples, grapefruit, tomatoes Dry fruits- peanuts, sunflower seeds
Seed Dispersal Seeds are dispersed in many different ways: Wind Water
Fruit is shaped for flight So tiny floats on the air Water Float and drift away Animals Eat and excrete Carry away and spit out Clumsy and drop their collection Bury and forget Get stuck of fur
Seed germination Seeds are dormant (inactive) until conditions are favorable and germination can then begin. Germination is the beginning of development of the new plant Requirements for germination Water Oxygen Favorable temperatures Other Acid of an animals digestive system Period of freezing Soaking in salt water Exposure to fire
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