Flowers
Flower organs
Most flowers have several stamens which are the male reproductive organs.
The female reproductive organ of a flower is the pistil.
Petals are usually colorful structures that can attract animals to pollinate the flower
Sepals protect the flower bud and can look like small leaves or flower petal
A stamen has two parts—a filament and an anther.
Inside the anther are cells that undergo meiosis and
then mitosis to form pollen grains.
The filament, also called the stalk, supports the
anther.
A pistil usually has three parts—a stigma, a style, and an ovary.
The style connects
the stigma to the ovary
The ovary contains one or more
ovules.
A female gametophyte develops in each ovule, and one
egg forms inside each female gametophyte.
Flower Adaptations
Flowers that have both stamens and pistils are called perfect flowers.
Flowers that are missing one or more of these organs are called incomplete flowers.
Flowers that have either stamens or pistils are called imperfect flowers
Flowers that have sepals, petals, stamens, and one or more pistils are called complete flowers.
When the petal number of a flower is a multiple of
four or five the plant usually is a eudicot
Monocots usually have flower organs
in multiples of three.
Pollination
Cross-pollinated flowers receive pollen from another plant
Self-pollinating flowers are able to pollinate themselves or another flower on the same plant
Many flowers that are pollinated by animals are brightly colored, have strong scents, or produce sweet nectar.
Flowers that are not brightly colored or do not have strong scents are usually pollinated by the wind.
Photoperiodism
the number of hours of uninterrupted darkness influences the flowering of some plants
A long-day plant flowers when it receives fewer hours
of darkness than its critical period.
An intermediate-day plant flowers as long as the number
of hours of darkness is neither too great nor too few.
short day plant when it is exposed daily to a number of hours of darkness that is greater than its critical period.
A day-neutral plant flowers regardless of the number
of hours of darkness as long as it receives enough light for
photosynthesis to support growth
winter, spring, or fall
pansies, poinsettias, and tulips
summer.
lettuce, asters, coneflowers, spinach, and potatoes.
sugarcane and
some grasses.
buckwheat, corn, cotton, tomatoes, and roses.