Flower

REPRODUCTIVE ORGANS OF TERRESTRIAL ANGIOSPERMS R. Perry MALIBU HIGH SCHOOL

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in terrestrial angiosperms. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Flowers give rise to fruit and seeds. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen.

In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to beautify their environment, but also as objects of romance, ritual, religion, medicine and as a source of food.

The reproductive organ of a terrestrial angiosperm is also know as

A FLOWER

MALE PART the STAMEN

FEMALE PART the PISTIL

pollen

stigma

anther filament

style ovary containing ovules

petals sepals pollen = sperm ovules = eggs

stem

MALE PART the STAMEN

FEMALE PART the PISTIL

male gametes produces pollen holds up anther

captures pollen holds up + growth of endostigma sperm produces ovules

female gamete attracts birds and bees

sperm + egg = new seed !

protect ovary holds flower up

SELF POLLINATION pollination

gravity

wind

fertilization

CROSS POLLINATION

wind

gravity pollination

birds bees

PLANT #1

PLANT #2

fertilization

WHICH IS BETTER FOR EVOLUTION THE SURVIVAL OF THE SPECIES? SELF FERTILIZATION: ONE PARENT - ONLY ONE SET OF GENES !

CROSS FERTILIZATION:

+

TWO PARENTS A MIXING OF TWO SETS OF GENES !

IMPERFECT

FL O W

COMPOSITE

ER S

PERFECT

?

PERFECT FLOWERS (bisexual) A perfect flower is a type of flower that has both pistillate (female) and staminate (male) parts. It does not require wind, insects or animals to pollinate.

IMPERFECT FLOWERS (unisexual) An imperfect flower does not have male and female parts in the same flower. Pollination requires the wind, insects, animals or other agents.

COMPOSITE FLOWERS Com`pos´i`tae (Bot.) A large family of plants, having their flowers arranged in dense heads of many small florets and their anthers united in a tube.

THE END