Chapter 2 Lesson 2 Plant Life Cycles
VOCABULARY
1. Pollination
2. Pollen
3. Embryo
4. Seed coat
5. Germination
6. Monocot
7. Dicot
8. Conifer
NOTES
What are seedless plant life cycles?
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All living things have life cycles.
A life cycle is a series of differing stages of development.
Plant life cycles include both an asexual and a sexual stage.
Alternation of generations-alternating between asexual and sexual reproduction.
Moss Life Cycles
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Begins with asexual reproduction.
Mosses grow thin brown stalks with capsules at the top.
Capsules contain tiny spores.
Spores are cells that can develop into a new plant without fertilization.
Spores that land is shady, moist soil are likely to grow.
In the sexual stage, the spore develops into the green, carpetlike adult plant.
Adult plant has male structures that produce sperm cells and female structures that produce
eggs.
Water carries sperm to female structure. This is where fertilization takes place.
Fertilized egg develops into brown stalk with a spore capsule.
The cycle continues.
Fern Life Cycle
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Begin life with asexual reproduction.
Produce spores on the undersides of their fronds, or leaves.
Spores are in clusters in a spore case.
Spore case opens and spores are released.
Spores grow into a small heart-shaped plant with male and female structures.
Sexual Reproduction now takes place.
Heart-shaped plant produces male and female sex cells.
Fertilization occurs and the fertilized egg forms a new plant.
New plant develops into a leafy fern.
Spore cases on the ferns’ fronds produce spores.
The cycle continues.
What are the parts of a flower?
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Flowering plants (angiosperms) are efficient food makers.
Tough, grow fast, and good at producing offspring.
Flowers are the reproductive organs of angiosperms.
Not all flowers are alike.
Complete flower- 4 main parts: petals, sepals, stamens, and pistils.
Petals-brightly colored outer parts of a flower.
Sepals-usually green, cover and protect the flower’s parts when it is a just a bud.
Stamen-male part of a flower.
Pistil-Female part of flower.
Flowers usually have more than one stamen made up of filament.
Filament-thin stalk portion of the stamen.
Anther-top of the filament, produces pollen grain which contain sperm cells.
Pistil is made up of a stigma, a style, and an ovary.
Stigma-opening at the top of the pistil.
Style- long, necklike structure that leads down to the ovary.
Ovary-houses the egg cells and it is the place where fertilization occurs.
Incomplete flower-missing one or more parts of a complete flower.
Perfect flower-has both stamens and a pistil.
o EX: lilies, gladioli, tulips, and most fruit blossoms.
Flower can be complete and perfect.
o EX: windflower
Imperfect flower-lacks either a stamen or a pistil.
o EX: willow trees, single corn plant.
What is the angiosperm life cycle?
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Before fertilization can occur, pollination must take place.
See pollination and pollen in your vocabulary section.
Pollen moves through pollinators.
o EX: bees, birds, and other animals.
Pollinators get nectar out of pollination.
Nectar- sweet liquid produced by flowers to attract pollinators.
Flowers have colorful petals, interesting shapes, and scents that appeal to pollinators.
Pollination Steps
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Flowers open and pollinators (bee) arrives.
Attracted to sugary nectar.
As the bee drinks, grains of pollen rub off on its body.
When the bee goes on to the next flower, some of that pollen rubs off the flower’s pistil.
Pollinations occurs.
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Animals are not the only means of flower pollination.
Some rely on the wind
o EX: grasses and some trees.
You can usually tell how a flower gets pollinated by looking at it.
Large, scented blossoms-Animals
Small, dull-Wind
Self-pollination-when a perfect flower with both male and female parts pollinates itself.
Cross-pollination- when pollen from one plant pollinates a flower on a different plant.
Both types can be carried out by wind or animal.
Fertilization takes place when the sperm and egg cell combine to form a seed.
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What is in a seed?
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Inside the ovary of a flower, the fused sperm cell and egg cell develop into an embryo.
Embryo grows inside a seed.
As the seed develops, the ovary enlarges until it becomes a fruit, which protects the seeds.
Three main parts of a seed
o Tiny embryo-offspring
o Cotyledon-food supply
o Seed coat-outer covering.
Seeds must be dispersed, or spread, in order to germinate.
Favorable conditions for growth: water, sunlight, and space.
Seed Dispersal
o Parachute-like structures/WIND
o Floating-WATER
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o ANIMALS
o BURRS-sticky hooks.
The most common seed-dispersal method is for the plant to surround the seed with a sweet,
fleshly fruit.
When eaten, fruits pass through animals’ digestive systems and get deposited in a new location.
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2 Groups of Flowering Plants
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Monocots-single cotyledon
 Petals come in groups of 3.
 EX: corn plants, orchids, and grasses.
Dicots- two cotyledons
 Petals come in groups of 4 or 5.
 EX: Bean plants and roses.
What is the conifer life cycle?
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Gymnosperm-plant with seeds, but not flowers.
EX: evergreens, pines, firs, cone-bearing trees.
Differ from angiosperms in 2 key ways.
o Produce cones for reproduction
o Have “naked” seeds.
 Their seed are not packaged inside a fruit like the seeds of flowering plants.
Single conifer will produce both male and female cones.
Smaller male cone release clouds of powdery pollen that blows in the wind.
Larger female cone produces a sticky fluid.
Pollination occurs when the pollen grain land on the sticky fluid.
Seeds have papery, winglike structures that help them whirl their way to the ground.
In a strong wind, these winged seeds can end up far from the tree they were launched from.
These seeds can then grow into new trees.