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Plants
A survey of Kingdom
Plantae
Characteristics of Plants
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All Plants are Producers Photosynthetic
Plants are Multicellular
Plant cells have cell walls
Plants are Non Motile
Plant Evolution
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Plants are thought to have evolved from
Green Algae.
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Modern Plants and Green Algae have
the same type of chlorophyll, similar cell
wall composition and both have starch
as their food storing polysaccharide.
Green Algae
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Green Algae may be unicellular or
multicellular and primarily live in aquatic
environments
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Modern Plants however are adapted to
life on land
Advantages of Life in Aquatic
Environment
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Constant source of water - no risk of
desiccation
Nutrients are readily available
Water provides support
Water is a medium for the transport of
gametes
They have a moist surface for gas
exchange
Life on Land
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In order to survive on land plants must
posses strategies or adaptations that
compensate for the aforementioned
advantages of life in water
Plant Classification
Plant Classification
Plants
Bryophtes
eg. Mosses
Tracheophytes
Spore producing
Eg. Ferns
Seed Producing
Gymnosperms
eg. Conifers
Angiosperms
Flowering plants
Bryophytes
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A common example of bryophytes are
mosses
Bryophyte Characteristics
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Have NO true roots, stems or leaves
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Gas exchange occurs through small
openings called stomates
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Have NO Vascular tissue
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Must live in moist areas
Usually Small in size - 2cm.
Are anchored to the ground by
structures called Rhizoids
Gametophyte generation is dominant
Each Gametophyte is a separate sex
Why are Bryophytes limited to
Moist environments
Sperm have to swim to egg
 Only posses a thin cuticle so they are
prone to desiccation.
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Why Bryophytes are Limited in
Size.
With no vascular tissue there is no
support for large sizes .
 Also due to no vascular tissue materials
are transported via diffusion…..this can
only occur over a small area.
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Reproduction In Bryophytes
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Bryophytes undergo what is called an
Alternation of Generations
 An
alternation between a haploid
gametopyte generation and a diploid
sporophyte generation.
Alternation of Generations in
Bryophytes
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See diagram on page 476
Tracheophytes
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Tracheophytes are characterized by the
presence of vascular tissue
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Have “True” Roots Stems and leaves
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There are two groups of tracheophytes:
Tracheophytes
spore producing
Seed producing
What is Vascular Tissue?
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Vascular tissue are parts of plants that
are responsible for the transport of
materials throughout the plant.
2 types of Vascular Tissue
 Xylem - transports water and minerals
 Phloem - transports “food”
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Spore Producing Tracheophytes
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An example of spore producing
tracheophytes are Ferns
Characteristics of Spore
Producing Tracheophytes
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Vascular tissue
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true roots,stems, and leaves
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Thicker cuticle then Bryophytes
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No seeds but spores
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Sporophyte generation is dominant,
Gametophyte generation is reduced
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Gametophyte generation still dependent
on water for reproduction
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Both sex organs on one gametophyte
Alternation of Generations in
Spore Producing Tracheophytes
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See page 477
Seed Producing Tracheophytes
Seed Tracheophytes
Gymnosperms
-Cone bearing
Angiosperms
- Flowering
Gymnosperms and Angiosperms
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These two groups of plants produce
seeds.
Both have no need for water for
reproduction and have true leaves,
stems and roots. (needles are leaves).
In both the sporophyte is dominant (the
plant is the sporophyte). The
gametophytes are microscopic.
Gymnosperms
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Conifers are gymnosperms. There seeds
are in the female cones while pollen
comes from the male cones.
They have advanced plant features (roots,
leaves, stems) and usually restricted to
harsh environments (cold). Why?
Thrive in cool climates, with poor soil,
often found in moist seashore areas.
Some gymnosperms have leaves.
Life Cycle
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They have a simple life cycle (page
479) and are often pollinated by wind.
Male gametophyte is the pollen grain
Female gametophyte is the Ovule
These gametophytes are contained
within cones.
Life Cycle
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Male cones release millions of pollen
grains.
If a pollen grain lands on the ovule of a
female cone a pollen tube will form
sperm will travel down the tube and
fertilize the egg.
Life Cycle
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A covering forms around the zygote and
the food supply to form a seed.
When seed ripen the cones will open
seeds have papery wings and are
dispersed by the wind.
Angiosperms
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These are the most advanced plants
and have adapted to a wide variety of
habitats (everywhere you see flowers,
you see angiosperms).
Angiosperms
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These are the flowering plants: the
reproductive structures of plants are
located within the flower.
Male and female sex organs are in
close proximity and are often placed to
take advantage of wind or insects.
Pollen moves from one place to another
to ensure fertilization of eggs. (see life
cycle on page 480).
Types of Flowers
Perfect Flowers
 Flowers that have both male and female
parts
Imperfect Flowers
 Flowers that have either male or female
parts
Fertilization of a Flower
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When a pollen grain lands on a stigma a
pollen tube forms
The pollen tube grows down through the
style
The tube nucleus directs the growth of
the pollen tube
The sperm nuclei enter the ovule
Fertilization of a Flower
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One sperm nucleus fuses with the egg
to form a zygote
The other fuses with the two polar
nuclei to form a cell that becomes the
endosperm (Food Source)
This is know as double fertilization
Seed Structure
After fertilization the ovule develops into a
seed.
Fruit
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After fertilization the ovary of the flower
enlarges forming the fruit. The seed is
contained in the fruit
As the fruit ripens the flower parts fall
away.
Reasons for the success of
Angiosperms
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1. Pollination is relatively easy (by wind,
insects or self pollination)
2. Flowers tend to attract insects (for
pollen or nectar
3. Seeds are protected by a seed coat
(allowing seeds to pass undigested
through most digestive tracts, then they
grow in the free fertilizer)
Reasons for the success of
Angiosperms
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4. Fruits are attractive to animals who in
turn help disperse seeds (above).
5. Seeds are able to suffer severe
conditions such as fire, freezing,
drought and then emerge when
conditions are again suitable.
6. Plants themselves have adapted to a
wide variety of habitats.
Types of Angiosperms
Angiosperms
Monocots
Dicots
Monocots vs Dicots
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Vascular tissue
Parallel veins in leaves vs Netted Veins
in leaves
Seeds
One Cotyledon vs Two Cotyledons
Flowers
petals in multiples of 3 vs petals in
multiples of 4 or 5
Monocots vs Dicots
Special Structures