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Life Cycle and Reproduction of Flowering Plants
6-2.5: Summarize each process in the life cycle of flowering plants (including germination, plant development,
fertilization, and seed production)
6-2.6: Differentiate between the processes of sexual and asexual reproduction of flowering plants
Sexual Reproduction in Plants
Sexual reproduction is a process that involves two parent plants
– New organism is different from the parents
– Offspring has DNA from both parents
1) First, pollen falls on a flower’s stigma.
2) Sperm cell + egg cell join together in the flower’s ovule.
3) The zygote develops into the embryo part of the seed.
Life Cycle Stages
All flowering plants (angiosperms) have similar life cycles
4 main stages of a plant’s life cycle:
1. Germination 2. Plant Development 3. Fertilization 4. Seed Production
1. Germination
Germination is the early stage of seed growth. Seed opens, roots grow down, stem and leaves grow upward.
Seeds need the right conditions to grow
– seed absorbs water from the environment
o water is the main ingredient for germination to occur
– Seeds can stay dormant (asleep) until ready to grow
– Light is not needed for germination
Roots grow down, stem and leaves grow up
2. Plant Development
Plant development is the process of a seed growing into a mature adult
plant
The plant grows the necessary reproductive structures to produce more
plants
Flowers: reproductive structures
– Have both male and female parts
– Attract pollinators (birds, bats, or insects) with smell and color
(and some with UV light radiation)
The male part is called the stamen and consists of:
– Filament: thin stalk
– Anther: pollen covered lobe at top of stalk
The female part is called the pistil and consists of:
– Stigma: sticky top where pollen grains land
– Style: stalk down which pollen tube grows
– Ovary: contains the ovule (egg cell)
Stamen: male reproductive parts. Pollen is produced in the anther at the top of the stalk-like filament
Pistil: female reproductive parts. Consists of a sticky stigma, a slender tube called the style, and a hollow structure called
the ovary, at the base.
Sepals: small, leaf-like parts of a flower; protect the developing flower. Neither a male or female part.
Petals: usually the most colorful part; pollinators are attracted to the color and scent. Neither a male or female part.
3. Fertilization
Fertilization is the joining of a sperm cell (pollen) and an egg cell (ovule).
Pollen: produced in the stamen
Ovule: egg cell in the ovary
Pollination
– the transfer of pollen from the male part of the plant (stamen) to the female part (pistil) of the plant
– can occur through wind, birds, bats, insects, etc.
Pollination vs. Fertilization
Pollination
- Pollen moving from a
stamen and landing on a pistil
-Transferred by: wind, bees,
birds, bats
Fertilization
-Pollen (sperm cell) coming
together with ovule (egg cell)
-Pollen tube begins to form
through the pistil and pollen
moves down it to the ovule
-Fertilized ovule becomes a
seed
4. Seed Production
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Seed: structure that contains an embryo (young plant) and its protective coating
An egg cell (ovule) that is fertilized will develop into a seed
The seed is protected by the fruit that grows around it
Types of Fruit Growing around a Seed
Fleshy: apples peaches, pears,
Pod: peas, beans
Shell: acorns, chestnuts, peanuts
strawberries
How seeds spread and travel
The fruit protects and also helps disperse seeds
– Animals: Seeds pass through digestive system and are dropped off. Bury seeds for
storage. Seeds stick to fur, feathers, and clothes.
– Water: Rain can knock seeds to the ground. Seeds can float on water and land in new
places (ex: coconuts).
– Wind: Many seeds are light enough to be moved by the wind (ex: dandelions).
Asexual Reproduction in Plants
Asexual reproduction is a process that involves only one parent plant
– produces offspring identical to the parent plant
Plants do not normally reproduce asexually. Asexual reproduction happens when
– There are no partners nearby
– The plant is damaged in some way
Asexual Reproduction: Vegetative Propagation
1. Bulbs and Tubers
Bulbs
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Tubers
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Big round buds made of stem and special types of leaves
Underground stems
Examples: onion, tulip, iris
Modified stem or root parts
“eyes” or buds of tubers grow into roots and shoots to produce a new plant
Example: potatoes
2. Runners
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Stems that run along the ground.
Long and skinny.
Connected to the parent.
Examples: centipede grass, ivy, strawberries
3. Stem Cuttings
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Planting a piece of a cut stem can form new roots
A full plant can grow from the
formed roots
Examples: pineapple, sugar cane
4. Roots
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Roots send out new shoots, called “suckers”.
Some plants can produce new plants from root pieces.
Examples: fruit trees, sweet potatoes
5. Leaves
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Some leaves can produce little plants
directly on their surface
Place the leaves on soil and a new plant can
grow
Example: African violets
Life Cycle and Reproduction Checking for Understanding Questions
1. What is the early stage of seed growth called?
2. The main ingredient for the start of seed growth is____. a. sunlight
b. water
c. soil
d. vitamins
3. True or False: Seeds will always start to grow right away.
4. Flowers are the ___________________________________________ structure of a plant.
5. Is pollen located on a male or female part?
6. On which structure is pollen located?
7. On which part of the pistil do pollen grains land?
a. Stigma b. Style
c. Ovary
d. Ovule
8. Where are egg cells (ovules) located in the flower?
9. When does fertilization occur?
a. once the pollen reaches the pistil
c. when the pollen joins the ovule
b. when the pollen tube starts to form
d. when the pollen moves through the style
10. Which part of a plant forms around the seed to make the fruit? A. leaves B. petals C. pollen D. ovary
11. When does germination take place for angiosperm seeds?
A. When the fruit or seed gets planted.
C. When the blossom becomes a fruit
B. When the blossom gets pollinated.
D. When the seed becomes a fruit
12. What happens after a blossom is pollinated?
A. Insects carry the seed to another plant.
C. A seed begins to grow inside the ovary
B. The blossom falls to the ground to germinate. D. Pollen falls to the soil and germinates
13. What does the fruit do for an angiosperm seed?
A. Fruit germinates the seed. C. Fruit protects the seed.
B. Fruit pollinates the seed.
D. Fruit breaks the seed.
14. Where do gymnosperm seeds germinate?
A. On the wind B. In cones
C. In flowers
D. In soil
15. Why are female cones sticky?
A. To hold the pollen
B. To attract insects
C. To hold the eggs
D. To stay on the tree branch
16. What do the pollen grain and the egg become during fertilization?
A. They form a sepal.
B. They form a new pistol.
C. They become honey.
D. They become a seed.
17. What does a pollen grain have to do in order to fertilize an egg?
A. Travel from the pistil to the stamen.
C. Fall through the filament to the anther
B. Germinate in the soil around the flower.
D. Travel from the stigma down the style to the ovary.
18. What are the three kinds of protection for a seed?
Match the kind of seed dispersal with the example. (Choices: burial, digestion, clinging)
19. Deer eating a seed plant. _____________________________
20. A person walking through a field gets prickly seeds stuck to their pants. _____________________
21. A chipmunk storing seeds underground. ___________________________
22. Where are the seeds of angiosperms? A. On cones
B. In the stem C. Inside fruit
D. Under the leaves
23. How are monocots and dicots different (review)?
A. Monocots have 1 seed leaf, dicots have 2 seed leaves.
B. Monocots are gymnosperms, dicots are angiosperms.
C. Monocots have branched veins, dicots have no veins.
D. Monocots’ flower petals are in multiples of 2, dicot’s are in multiples of 7.
24. What is the process of growing new plants from plant parts?
25. Which is NOT a term involved with asexual reproduction? a. pollination b. bulbs and tubers c. runners d. stem cuttings
26. Why would a plant use asexual reproduction to create offspring?
Identify if sexual (S) or asexual (AS) 27. One parent, identical offspring _______28. Two parents, unique offspring _____