Download Plant Evolution and Classification Power Point File

I. Plants and the Colonization of
the Land
A. An Introduction to the Plant Kingdom
1. Characteristics of Plants
a) Autotrophic: Contain chlorophyll a
& b, carotenes
b) Multicellular, cell walls contain
cellulose
c) Eukaryotic, Nucleus, membrane
bound organelles, starch stored in
plastids
2. A generalized View of a Plant
Lifecyle
a) Alternating generations between a sporophyte
which is a diploid spore producing generation
and a gametophyte which is a haploid gamete
producing plant
b) All modern plants are heteromorphic- their
sporophyte and gametophyte generations differ
in morphology
c) One main trend in evolution of plants is toward a
reduction of the haploid generation and the
dominance of the diploid generation
Plant Life Cycle:
Lower plants have a dominant gametophyte generation while
higher plants have a dominant sporophyte generation
Sperm
Gametophyte Generation
Haploid
In Water
Egg
Spores
Sporophyte Generation
Diploid
Zygote
B. Major Events
in Plant Evolution
Evolution of Land Plants
1. Non-vascular plants evolved
from green algae. Therefore, nonvascular plants must have
adaptations that allow waterdwelling algae to overcome the
problems of living on land and to
best utilize the resources available
there.
What is going on?
What problems do these plants face on land?
Which group has an advantage over the
other group? Why?
Plant Group 2
Plant Group 1
Does plant group #3 have an advantage
over groups 1 & 2? If so, what is it?
Plant Group 3
Group 2
Group 1
What advantages does plant group #4
have over the other plants?
Plant Group 4
Group 3
Group 2
Group 1
All lower plants (groups 1-4) have a significant
gametophyte generation. That’s right, they reproduce
like animals using sperm and egg! How do sperm travel
to the egg?
Water of course!
Therefore, these plants must be located near water or
inhabit areas with abundant rainfall.
Group 3
Group 2
Group 1
Plant Group 4
Pollen
How do higher plants
assure that their gametes
reach their significant other
even when they live in dry
areas?
2. Moving onto land caused plant cells to dehydrate
and the following structures evolved to reduce
water loss
a) Cuticle- waxy layer that prevents evaporation
from plant tissues above ground
b) Stomata- openings through the waxy layer that
allows gas exchange
c) Gametangia- protective jacket of cells that
prevent the gamete from dehydrating
d) Rhizoids- epidermal cells with elongated
regions to anchor the plant and provide surface
area for water absorption
e) Lignin- material embedded in cellulose to
strengthen it
Major Events in Plant Evolution
3. Development of vascular tissues- tissues that
conduct water and minerals allowed plants to
grow tall
a) Xylem- dead cells that conduct water
b) Phloem- living cells that conduct sugars, amino
acids and other nutrients
4. Reduced gametophyte generation allows the
sporophyte to protect the gametophyte from
drought, UV radiation and provide it with
nutrients
Major Events in Plant Evolution
5. Production of pollen allows the male
gametophyte to be protected by a tough coat of
cells and can transport the sperm though the air.
Pollen replaced swimming sperm
6. Origin of the seed- plant embryo packaged with
nutrients.
7. The emergence of Angiosperms- flowing
plants that have protective coats on their seeds
and reproductive organs that aid pollination
II. Classification of the
Plant Kingdom
Multicellular, Eukaryotic and Autotrophic
Algae
Bryophytes
Water Dwelling
Land dwelling mosses,
liverworts, hornworts
Tracheophytes
Have Vascular tissue
Lack vascular tissue
Seedless
Seed Producing
Seedless Tracheophytes
Psilophyta: Sphenophyta: Lycophyta:
Pterophyta:
Lack roots
Lack roots and
Lack roots and
(have rhizoids), have small leaf- have small leafand have no
like structures
like structures
leaves. Ex.
called microphyls. called microphyls
Whisk ferns
Ex. Horse tails Ex. Clubmosses
have fronds
(macrophyls) and
rhizomes (underground stem
modified for
water absorption)
Ex. Fern
Seed Producing Vascular Plants
Gymnosperms: Have true
Angiosperms: True roots,
roots, stems, leaves, pollen
and seeds without a seed coat.
Ex. Conifers and Evergreens
stems, leaves, flowers, fruits
and seeds with seed coats. Ex.
Flowering Plants