Transcript Plant Classification

Plant Classification
Alternation of generations
• Sporophyte (diploid)
– Begins when
sperm fertilizes
egg (zygote)
– Diploid zygote
divides by mitosis
to create a mature
sporophyte
– Meiosis produces
haploid cells called
spores
– Haploid spores
released
Alternation of generations
• Gametophyte (haploid)
– Begins with spores
created by meiosis
– Spore grows into
gametophyte
• Male gametophyte
creates sperms
• Female gametophyte
creates eggs
– Sperm & egg create
diploid zygote
(process repeats)
Group 1: Seedless, Nonvascular Plants
• Live in moist
environments
• Liverworts
• Hornworts
• Mosses
Mosses
• Nonvascular,
seedless
• Grow low to ground
to retain moisture
• Lack true leaves
– Leaf-like structures
only 1 cell thick
• Rhizoids anchor into
soil
• Early inhabitant of
new ecosystems
(succession)
• Gametophyte phase
– Dominant stage
– Carpet of moss
growing near ground
Moss Life Cycle
• Archegonium:
produces female egg
• Antheridium:
produces male
sperm
– Sperm swims through
water to fertilize egg
• Sporophyte phase
– Stalk grows up from
the gametophyte
– Sporangia houses
haploid spores
– Spores land and new
gametophyte grows
See appendix B in your text book
1) Moss
gametophytes
grow near the
ground
(haploid stage)
2) Through water,
sperm from the male
gametophyte will
swim to the female
gametophyte to
create a diploid
zygote
3) Diploid sporophyte
will grow from the
gametophyte where
the zygote is located
...
sporophyte
gametophyte
4) Sporophyte will
create and release
haploid spores
5) Spores land
and grow into
new
gametophytes
6) The process
repeats
gametophyte
ground
Group 2: Seedless, Vascular Plants
• Vascular system
allows nutrient
transport to greater
heights
• Club mosses
• Horsetails
• Ferns
Ferns
• Seedless, vascular plants
– Vascular: allows taller growth
• Rhizoids: underground stems draw nutrients
• Fronds: leaves uncurl
– sporangia on underside
• Sori: clusters of sporangia
Fern Life Cycle
• Sporophyte phase
– Dominant stage
– Sporangia produces
haploid spores
– Spores released into air
• Gametophyte phase
– Spore grows into
prothallus
• Archegonium: produces
female egg
• Antheridium: produces male
sperm
See appendix B in your text book
– Sperm swims to egg
– Zygote begins sporophyte
stage
1) Sporophyte creates and releases haploid spores
.
.
. .
Adult
Sporophyte
(diploid)
ground
2) Spores land in the soil
ground
3) From the haploid spores, a prothallus (haploid gametophyte) grows in the soil
-- Rhizoids anchor
Let’s zoom in
ground
4) Sperm swim through water from the antheridium to the archegonia
Let’s zoom back out
5) Diploid sporophyte (fiddlehead) grows from the prothallus
-- prothallus eventually dies
ground
6) Fiddlehead uncurls into fronds of ferns.
7) Cycle repeats
-- Sporangia creates spores to be released
.
.
.
ground
.
Group 3: Seed producing, Vascular Plants
• Gymnosperms
– Cycads
– Ginko
– Conifers
• Angiosperms
Group 3: Seed producing, Vascular Plants
• 1) Seed plants don’t depend
on water to reproduce
– Pollen (contains sperm)
combines with egg
– Egg hardens into a seed
• 2) Nourishment and
protection
– Nourish: Nutrients inside
seed for the embryo
– Protection: Hard shell
• 3) Allow dispersal
– Carried by wind, water,
animals
Group 3: Seed producing, Vascular Plants
• Type 1: Gymnosperms
• Seeds not enclosed in a
fruit
– produced inside cones
• Cone = reproductive
structure
• Male cones: produce
pollen
• Female cones: produce
eggs and seeds
Group 3: Seed producing, Vascular Plants
• Gymosperm example:
Conifers
– Cone plants
– Needle-like leaves
– Common to lumber
industry
– Evergreen, Pine,
Redwood, Cedar
Conifer Life Cycle
• Sporophyte phase (dominant)
– Cones grow on tree
– Female cones
• Megaspores inside
archegonia (gametophyte)
– Male cones
• Microspores (gametophyte)
released from antheridia
• sticks to archegonium
• Pollen tube grows from
pollen
• Sperm travels down pollen
tube (zygote/seed created)
• Sporophyte stage restarts
1) Male and female seed cones grow in adult sporophytes
2) Pollen grains released from the male seed cones
-- Pollen is the male gametophyte
Let’s zoom into the female seed cone
3) Pollen grain sticks to the female ovule
4) Pollen tube grows from the male spore
5) Two nuclei transfer into female spore
- one fertilizes the egg
6) Diploid embryo develops (sporophyte stage restarts)
7) After seeds harden,
the cone reopens and
the seeds are
released
8) Seed will land
ground
9) Seedling grows into (sporophyte)…the cycle repeats
ground
female
male
Group 3: Seed producing, Vascular Plants
• Type 2: Angiosperms
(flowering plants)
• Flower = reproductive
structure
– Protects gamete
and fertilized eggs
• Seeds enclosed in a
fruit
– Fruit: Plant ovary
– Often attract
animals to disperse
the seeds inside
Angiosperm types
(flowering plants)
• 2 groups: Monocots and Dicots (based on seed
type)
• Cotyledon: embryonic leaf
• Monocots: embryo with 1 seed leaf
• Dicots: embryo with 2 seed leaves
Monocots vs. Dicots
Angiosperm Life Spans
• Three Life Span Types:
• Annuals
– 1 year: Mature…produce
seeds…die
• Biennials
– 1st year: produces short
stem, low growth leaves,
food reserves
– 2nd year: taller stem, leaves,
flowers, seeds
• Perennials
– Live for more than 2 years
Flowers
• Reproductive
structure of flowering
plants
• Sepals
– outer ring of leaves
– protection
• Petals
– Inner ring of leaves
– Brightly colored to
attract pollinators
• Open petals & sepals
reveal male and
female structures
Flowers
• Female Carpal
– Inner most part
– Ovary: within the
base (female
gametophyte)
– Style: long stalk
– Stigma: sticky
tip, collects
pollen
• Male Stamen
– Surrounds carpal
– Filaments: long
stalks
– Anther: produces
pollen (male
gametophyte)
• 1) Flower matures and opens
• 2) Microspores (male gametophytes) created in
the anthers
In the Anthers
• Meiosis makes 4 microspores
• In each microspore
– Nucleus splits in two
– 1 nucleus: forms pollen tube
– 1 nucleus: splits again to make 2 more nuclei
• 1 nucleus: fertilizes the egg
• 1 nucleus: fuses to make endosperm
• 3) Microspores continue to develop
• 4) Ovaries divide by meiosis to create
megaspore
In the Ovules
• Meiosis makes 4
megaspores (only 1
survives)
• In megaspore
– Mitosis creates 8 nuclei
– 1 nucleus: egg cell
– 2 nuclei: form embryo
sac
– 5 nuclei: disintegrate
Microspore lands on stigma
Microspores (pollen) released
Microspores (pollen) land on the stigma
Pollen tube and 2 nuclei transfer into the ovule
..
• 5 & 6) Pollen tube grows from pollen
– Two sperm nuclei follow down the pollen tube
• 7) Double fertilization:
– 1 sperm nuclei fuses w/ egg (zygote created)
– 1 sperm nuclei fuses w/ the embryo sac (endosperm created)
• 8) Ovule hardens to form seed
Fruit Production
• In the seed
– Embryo
– Endosperm
• Surrounding ovary grows into a
fruit
• Fruit attracts animals to eat and
spread the seeds
Fruit seeds in fox droppings
9) Seed germinates…cycle repeats