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Gymnosperms
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Gymnosperms are vascular
plants that produce cones.
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Their seeds have a protective seed coat and a
food supply for the embryo.
Seeds are also “Naked” – the seeds are exposed
and not enclosed in a fruit
Unlike the mosses and ferns, Gymnosperm
sporophytes grow within the gametophyte
structures and not independently.
1. Division Ginkgophyta – Ginkgo
 Only one species is still living. The Maidenhair
tree. (Also known as the silver apricot or
ginkgo)
 Leaves are fan-shaped.
 They are Dioecious – male and female cones
are produced on different plants. (females have
seeds that stink but are edible)
2. Division Cycadophyta - Cycads
 Grow to be about 15 feet tall, with an unbranched stem.
 They are pollinated by beetles instead of wind,
because their pollen is to large to travel in the
air.
 They are dioecious.
 Male and Female cones are huge, with some
species measuring up to 3’ 3” and weighing
over 100 pounds. The female cone is covered in
wooly hair.
3. Division Gnetophyta
 Have vessels in their xylem, which is unique to
gnetophytes.
3 Genera:
A. Ephedra – They
ooze a sticky fluid to
catch pollen. The leaves
turn brown shortly after
appearing. They have
ribbed stems.
B. Gnetum – Vine-like broad leaves found in
South America, Africa and Southeast Asia.
C. Welwitschia - only one species, found in
Southwest Africa. Only two leaves per lifetime.
Can grow for 100 years, by surviving off of the
dew and condensation from fog.
4. Division Pinophyta
 Also called Conifers,
because they produce
cones
 Ex.: Pine, Cedar,
Fir, Spruce
 The largest genus
of conifers is Pinus,
with over 100
species.
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Leaves are needle-like and in clusters called
fascicles. These fascicles usually have between
2 and 5 leaves.
Pinophytes can survive harsh environments,
including low temperatures and high wind
areas.
The fascicles absciss (fall off) within 2 to 5 years
of maturity.
They are “evergreen” because there is always
some leaves on a evergreen tree.
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They have resin canals, which are tubes lined
with special cells that secrete resin/sap. The
resin is used to protect the tree from bacteria
and fungus. It is also produced in response to
injury.
Pines are considered softwoods because they
do not have a thick cell wall.
Have large growth rings, due to rapid growth
each season.
Bark is relatively thick. Redwoods have bark
that is 2 feet thick.
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They produce two kinds of Strobili
or cone.
1. Pollen cones – “ Male Strobili” –
are produced only in the spring
They produce microsporangia at the
base of the cone that will develop into four
microspores. These microspores develop into
pollen grains.
 Pollen grains are made of four cell with air space so
that they can be transported by wind
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2. Seed Cones – “ female Strobili” –
these are the large, woody cones.
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The megasporangia are located within
the ovules and the megaspores are
Produced at the base of the cone from
the megasporangia.
The megasporangia, also, helps to
create the nucellus which surrounds and encloses
the integument which helps to form the seed coat.
Within the integument there is a pore called the
micropyle that helps to direct sperm to the egg.
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The megasporangia produces 4 large
megaspores produced by each cone. 3 of which
quickly die off.
The remaining megaspore develops into the
female gametophyte
As the female gametophyte develops it
produces 2 to 6 archegonia.
Each archegonia contains one single large egg.
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It takes several seasons for the seed cone to
mature, but an immature cone can spread apart
to allow pollen to enter.
When the pollen enters it sticks to the pollen
drops which is a sticky fluid that will evaporate
to pull the pollen to the micropyle.
After Pollination, the scales close-up to protect
the ovules.
It takes about a month after pollination for the
megaspores to mature and up to a year for the
archegonia to develop.
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The pollen grains are immature male
gametophytes.
They produce a pollen tube that will grow and
digest it’s way through the nucellus.
While the pollen tube grows, 2 of the 4 original
cells enter the tube.
One of the 2 cells, generative cells, divides to form
a spermatogenious and a sterile cell.
The spermatogenious cell then divides to form 2
sperm cells.
A mature male gametophyte is made of the pollen
grain, the pollen tube, and the 2 sperm.
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About 15 months after pollination, the pollen
tube arrives at the egg to discharge all the
contents.
1 sperm unites with the egg to form a zygote,
the other sperm dies.
The zygote turns into a embryo that is
nourished by the female gametophyte.
The embryo forms seeds with thin wings from
the cone scales, that help the seed disperse.
When the seed is buried it forms a new young
sporophyte or seedling.
Angiosperms
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Angiosperms- Vascular plants that produce
flowers
Angiosperm literally means “Vessel Seed.”
The vessel is the carpel/pistils which is an
enrolled leaf with seeds along the margins.
These carpels are the female reproductive
structure of the flower.
Seeds develop from the ovule and the ovary
makes the fruit.
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All Angiosperms are in Division
Magnoliophyta.
Only 2 Classes:
1. Magnoliopsidia – Dicots – 2 Cotyledons
2. Liliopsidia – Monocots – 1 Cotyledons
(Cotyledons are the seed leaves of the embryo,
which store and help to make food.)
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The members of the angiosperm group are
very diverse. They include grasses, shrubs,
trees, parasitic plants(live off of other
organisms) and saprophytic plants ( live off of
dead organisms).
The sporophyte stage is once again the
dominant life cycle stage, just as in the
gymnosperm
Heterospory- They produce two types of
spores.
FEMALE:
 Female gametophytes are formed in the ovule which is
a part of the ovary that will develop into the seed. ( The
ovary is found at the base of the pistil/carpel in a
flower)
 The megasporocyte undergoes meiosis within the
ovule to form four megaspores, three quickly die.
 The megaspore divides by mitosis until there are 8
nuclei, without any cell walls dividing the nuclei and
the cell now becoming very large.
 As the cell grows, the outer two layers form the
integument which becomes the seed coat and a pore
called the micropyle
 The 8 nuclei form 2 groups on opposite ends of the cell.
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Two nuclei fuse together in the middle to form
the Central Cell Nuclei and cell walls form
around the remaining nuclei.
On the end closest to the micropyle there is an
egg and 2 synergids that are later destroyed.
The other end contains three antipodals, that
have no known function and are also later
destroyed.
The Female Gametophyte is made of a large sac
of seven cells with 8 nuclei and is now called a
megagametophyte
MALE:
 The male gametophyte is found in the anther of
the flower.
 There are four patches of tissue containing the
microsporocytes that each undergo meiosis to
form a quartet of microspores.
 These spores end up forming four pollen sacs
in the anther, and as the anther matures the
walls between the pollen sacs break down
forming two larger sacs.
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After undergoing meiosis, these two pollen
sacs must undergo the following 3 things to
develop into a pollen grain:
1. The nucleus divides by mitosis once.
2. The members of each quartet separate.
3. A two-layered wall develops around each
microspore.
Once the pollen grain has formed, it contains
an outer layer, exine, that contains chemicals
that allow it to only pollinate the correct
species.
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Each pollen grain has a thin pore-like area
called the aperature and two nuclei One of
which, the spermatogenious nuclei, divides to
form two sperm nuclei.
The mature male gametophyte is made up of
the pollen grain and three nuclei, two sperm
and one tube nuclei.
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Pollination- Transfer
of pollen from the
Anther (male) to the
Pistil (female)
Self-Pollination- Pollen is
transferred to the pistil from
the anther on the same
plant.
Cross-Pollination - Pollen is
transferred to the pistil from
the anther on a different
plant.
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Fertilization- the
combining of sperm and
egg.
5 Main Pollinators:
1. Bees
2. Birds
3. Bats
4. Butterflies
5. Beetles
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Fertilization takes place after pollination and
pollen has landed on the pistil.
The pollen grain absorbs part of the stigma, which
is the top portion of the pistil, and the pollen tube
comes out of one of the aperatures.
Once the tube reaches the micropyle, the pollen
grain, which includes two sperm nuclei, discharges
it’s contents into the tube.
The pollen tube grows until it reaches the female
gametophyte, where it enters into the
gametophyte, destroying the synergids and
releasing it’s contents.
Pollen Tubes
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Then Double Fertilization occurs. This process
is unique to angiosperms and is also called
double fusion.
During double fertilization two things occur:
1. One sperm unites with the egg to form the
zygote
2. One sperm unites with the Central Cell
Nuclei to form a 3N (3 sets of chromosomes)
nutritive tissue, called the endosperm
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In monocots, the endosperm forms
the part of the seed in dicots, the
endosperm provides nutrients to
the embryo.
In both monocots and dicots the
integument hardens and becomes
the seed coat
All the remaining nuclei are destroyed the
ovule becomes the seed and the ovary matures
into a fruit.
Embryo
Angiosperm Families
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There are more than 300 angiosperm families.
Each family is distinguished from each other
based on flower and fruit structures.
1. Buttercup- There are 1500 different species, their
flowers have numerous stamens (male) and pistils
(female) reproductive organs. Most are found in
northern temperate and arctic regions.
Ex. Buttercup, Columbine
2. Laurel - Made of 1000 species, without petals It is
made of mostly tropical shrubs and trees.
Ex. Bay Tree, Sassafras, Avocados
3. Poppy – Found North of the equator, are usually
planted as ornamental plants and they all produce an
alkaloidial drug.
Ex. Bloodroot, Opium
Laurel
Columbine Buttercup
Avocado
Bloodroot
Opium
4. Mustard- They have four petals that are
arranged to form a cross.
Ex. Cabbage, Broccoli
5. Rose – Contains more than 3000 species. The
non-reproductive parts of the flower are fused
to form a cup.
Ex. Fruits.
6. Legume – This is the third largest class with
13000 species.
Ex. Peas, nuts, beans
Mustard
Rose
Legume
7. Spurge – Found in temperate regions. They are
unisexual. They produce a milky latex and
most are poisonous
Ex. Poinsettia
8. Cactus – They are native only to North America
and are found in drier subtropical regions.
Ex. cactus
9. Mint – Most produce an aromatic leaf and stem.
Ex. Rosemary, thyme, sage, oregano
Spurge
Poinsettia
Christmas Cactus
Cacti
Mint
Oregano
Rosemary
Sage
10. Nightshade – Have over 3000 species that are
herbs, shrubs, trees and vines
Ex. Tomato, potato, eggplant
11. Carrot – Found all over the Northern hemisphere.
Flowers tend to be small and numerous
Ex. Carrot
12. Pumpkin – found in tropical and subtropical
regions. They are unisexual edible plants.
Ex. Squash, pumpkin, watermelon
13. Sunflower – The 2nd largest family, with 20,000
species.
Ex. Sunflower, Marigold, Lettuce
Nightshade
Tomato
Pumpkins & Squash
Carrot
Sunflower
1. Grass- The largest family in terms of individual
plants. And the most widely distributed
Ex. Wheat, rye, barley
2. Lily – Have large flowers that usually have
parts in multiples of 3
Ex. Lily, daffodil
3. Orchid – The largest family in terms of
individual species with over 35,000 species.
Ex. Orchids
Wheat
Barley
Rye
Lily
Calla Lily
Orchid