The Diversity of Plants
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Bryophytes
Tracheophytes
seed plants
Liverworts
Mosses
Ferns
Gymnosperms
Angiosperms
Plant Evolution
(F 21.1 p. 406)
Ancestral green alga
Green Algae Gave Rise to Plants
Plant Ancestors Lived in Fresh Water
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2005
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Key Features of Plants
• Alternating Multicellular Haploid &
Diploid Generations
– Alternation of generations in plants (F21.2 p. 407)
– More Recently Evolved Plants Have
Smaller Gametophytes
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gametophyte
(n)
n sperm
Haploid
spores n
n
n
n
FERTILIZATION
MEIOSIS
spore mother cell
egg
n
2n
Diploid
2n zygote
2n
haploid
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2005 Pearson Prentice Hall, Inc.
sporophyte
(2n)
embryo
Key Features of Plants
• Multicellular, Dependent Embryos
• Plants Are Adapted to Life on Land
– Bodies Resist Gravity & Drying
– Embryos Are Protected
– Sex Cells May Disperse Without Water
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Features of the Major Plant Groups
T21.1 (p. 408)
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Major Groups
of Plants
Bryophytes
• Lack
Conducting
Structures
– Bryophytes
(F 21.3 p. 409)
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capsules
Major
Groups
of Plants:
Bryophytes
Life cycle
of a moss
MEIOSIS
(F21.4 p. 410)
emerging
sporophyte
capsules
Protected
Reproductive
Structures
FERTILIZATION
emerging
gametophyte
leafy gametophyte
haploid
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diploid
capsules
MEIOSIS
emerging
sporophyte
capsules
FERTILIZATION
emerging
gametophyte
leafy gametophyte
haploid
diploid
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Major Groups of Plants:
Vascular Plants
• Conducting Vessels That Also Provide
Support
• The Seedless Vascular Plants
– Club Mosses, Horsetails, and Ferns
– Club Mosses and Horsetails Are Small and
Inconspicuous
• Some seedless vascular plants
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(F21.5 p. 411)
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sporophyte
masses of
sporangia
sporangium
Ferns:
BroadLeaved
More
Diverse
leaf
MEIOSIS
root
stem
FERTILIZATION
Life cycle of a
fern
(F21.6 p.
412)
gametophyte
haploid
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Major Groups of Plants
• Seed Plants
• Dominate the Land
• Aided by Two Important Adaptations: Pollen
and Seeds
– Seeds
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(F21.7 p. 413)
embryo
stored
food
Pine seed
(gymnosperm)
seed
coat
Bean seed
(angiosperm)
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Major Groups of Plants
• Gymnosperms: Nonflowering Seed Plants
– Conifer Seeds Develop in Cones
• Life cycle of the pine
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(p. F21.8 414)
scale of
female cone
male
cone
mature
sporophyte
female
cone
scale of
male cone
ovule
spore-forming cell
MEIOSIS
seedlings
MEIOSIS
female
gametophyte
seed
embryo
haploid
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egg cell
pollen
tube
FERTILIZATION
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Major Groups of Plants
– Ginkgos and Cycads
• Less Abundant
• Two uncommon gymnosperms
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(F21.9 p. 415)
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Major Groups of Plants
• Angiosperms: Flowering Seed Plants
– Angiosperms
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(F21.10 p. 417)
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Major Groups of Plants
– Flowers Attract Pollinators
• Life cycle of a flowering plant
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(F 21.11 p. 418)
seedling
flower
stigma
anther
mature
food source sporophyte
embryo
seed coat
seed
ovule
sporeforming
cell
anther contains
cells that form pollen
each seed developed
MEIOSIS
from one ovule
pollen grain
ovule
MEIOSIS
stigma
pollen
tube
FERTILIZATION
pollen
(male
gametophytes)
sperm nuclei
female gametophyte
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egg cell
spore
haploid
diploid
Major Groups of Plants
– Fruits Encourage Seed Dispersal
– Broad Leaves Capture More Sunlight
• Two ways of coping with the dryness of winter
(F 21.12 p. 419)
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Major Groups of Plants
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