Lesson 2 - Flowers - Lecture Notes

Flowers
Copyright © McGraw-Hill Education

Flower Organs

• Flowers have organs for protection, support, and reproduction.

• In general, flowers have four organs: sepals, petals, pistils, and stamens.

Multiple Select

Flowers have organs for...(Choose all thay apply)

• protection

• decoration

• support

• reproduction

Flowers
Copyright © McGraw-Hill Education

Flower Organs

• Sepals protect the flower bud and can look like small leaves or petals.

• Petals are usually colorful and attract pollinators/give them a place to land.

• Stamens are the male reproductive structure, the female reproductive structure
is called the pistil.

Multiple Choice

_______ are the male reproductive structure, the female reproductive structure is called the ______.

• stamens, pistil

• Petal, pistil

• pistil, stamens

• testes, ovaries

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Structural differences

• Flowers that have sepals, petals, stamens, and one or more pistils are called
complete flowers.

• If a flower is missing one or more of these organs, it is an incomplete flower.

• Flowers that have both stamens and pistils are perfect flowers

• Flowers that only have functional pistils or stamens are called imperfect flowers.

Multiple Choice

Flowers that have both stamens and pistils are called ____ flowers.

female

• male

• imperfect

• perfect

• hermaphrodite

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Structural differences

• The number of flower organs distinguishes monocots from eudicots.

• Monocots generally have organs in multiples of three.

• Eudicots usually have organs in multiples of 4 or 5.

• All organs tend to occur in the same multiple of three, four, or five.

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Pollination mechanisms

• Flower adaptations that relate to pollination include flower size, shape, color,
and petal arrangements.

• Self pollination: flowers can pollinate themselves or other flowers on the same
plant.

Multiple Select

Flower adaptations that relate to pollination include which of the following?

(Choose all that apply)

• flower size

• shape

• color

• petal arrangements

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Pollination mechanisms

• Cross pollination: flowers rely on pollinators for reproduction.

• Animal pollination: flowers are brightly colored or strongly scented to attract
pollinators

• Wind pollination: flowers lack showy or fragrant flowers, produce large
amounts of lightweight pollen.

Multiple Choice

What is the likely method of pollination for flowers lacking bright colors and stong smells?

• cone fertilization

• animals

• spores

• wind

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Photoperiodism

• Some plants only flower in response to a specific number of hours of
uninterrupted darkness.

• This flowering response is known as photoperiodism.

• Flowering plants are divided into four different groups based on the critical
period, which is based on the amount of daylight.

Multiple Choice

flowering in response to a specific number of hours of uninterrupted darkness is a flowering response known as...

• nocturnism

• photoperiodism

• werewolfism

• heliotropism

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Short-day photoperiodism

• A short-day plant (long-night plant) flowers when exposed daily to a number of
hours of darkness that is greater than its critical period.

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Long-day photoperiodism

• A long-day plant (short-night plant) flowers when the number of hours of
darkness is less than its critical period.

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Intermediate-day photoperiodism

• An intermediate-day plant flowers as long as the numbers of hours of darkness is
neither too great or too few.

Multiple Choice

An intermediate-day plant flowers...

• as long as the numbers of hours of darkness is neither too great or too few.

• when exposed daily to a number of hours of darkness that is greater than its critical period.

• when the number of hours of darkness is less than its critical period.

Flowers
Copyright © McGraw-Hill Education

Flower Adaptations

Day-neutral photoperiodism

•A day-neutral plant flowers over a range in the number of hours of darkness.

Multiple Choice

Which of these plants flowers during the summer?

• long night

• short-day

• intermediate-day

• long-day