Biology, Seventh Edition
Solomon • Berg • Martin
Chapter 27
The Plant Kingdom:
Seed Plants
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Features of seeds
• Primary means of reproduction
and dispersal of
–Gymnosperms
–Angiosperms
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Gymnosperm
and angiosperm
evolution
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Features of seeds, cont.
• Seeds are reproductively superior
to spores
–Embryonic development is further
advanced
–Seeds contain an abundant food
supply
–Each seed has a protective seed coat
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• The life cycle of a pine
• A pine is a mature sporophyte
• Pine gametophytes are small and
nutritionally dependent on sporophyte
• Pine is heterosporous and, in
separate cones, produces
–Microspores
–Megaspores
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• The life cycle of a pine, cont.
• Male cones produce microspores
• Microspores develop into pollen
grains
• Pollen grains carried by air to
female cones
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Male and
female cones
in Pinus
contorta
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• The life cycle of a pine, cont.
• Female cones produce
megaspores by meiosis
• One megaspore develops into a
female gametophyte in a
megasporangium
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• The life cycle of a pine, cont.
• After pollination, pollen tube
penetrates megasporangium
• Pollen tube reaches egg in the
archegonium
• After fertilization, zygote develops
into embryo
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Life cycle
of pine
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Features distinguishing
gymnosperms from bryophytes
and ferns
• Vascular plants with seeds
–Totally exposed or
–On cones
• Produce wind-borne pollen grains
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• The four phyla of gymnosperms
• Phylum Pinophyta
• Phylum Cycadophyta
• Phylum Ginkgophyta
• Phylum Gnetophyta
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Conifers
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Phylum Pinophyta
• Conifers that produce
–Wood
–Bark
–Needles
–Seeds in cones
• Most are monoecious
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Phylum Cycadophyta
• Look like palms or ferns
• Dioecious, but reproduce with
pollen and seeds in conelike
structures
• Once numerous, now few
members left
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Cycads
A female coontie
produces seed cones
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Cycads
This female cycad in
South Africa has a
trunk that reaches a
height of about 9 m.
Note immense seed
cones, to 0.8 m long
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Phylum Ginkgophyta
• Sole member is Ginkgo biloba
• Deciduous
• Dioceious
• Female ginkgo produces seeds
directly on branches
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Branch from a female ginkgo, showing exposed
seeds and distinctive leaves
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Gnetophytes
• Consist of three genera
–Gnetum
–Ephedra
–Welwitschia
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Gnetophytes, cont.
• Unique among gymnosperms,
sharing traits with angiosperms
–Vessel elements in their xylem
–Cone clusters resemble flower clusters
–Life cycle details resemble those of
angiosperms
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Leaves of Gnetum gnemon
resemble those of flowering
plants
Male Ephedra has pollen
cones clustered at the nodes
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
A specimen of Welwitschia mirabilis living in Namib
Desert, Namibia – survives on fog
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Angiosperms (phylum
Magnoliophyta)
• Vascular plants that produce flowers
and seeds enclosed within a fruit
• The most diverse and successful
group of plants
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Angiosperms (phylum
Magnoliophyta), cont.
• Flower may contain
–Sepals
–Petals
–Stamens
–Carpels
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Angiosperms (phylum
Magnoliophyta), cont.
• Ovules are enclosed within an
ovary
• After fertilization
–Ovules become seeds
–Ovary develops into a fruit
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Floral structure
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Life cycle of an angiosperm
• Sporophyte generation is
dominant
• Gametophytes are
–Reduced in size
–Nutritionally dependent on
sporophyte generation
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Life cycle of an angiosperm,
cont.
• Heterosporous
• Within the flower, they produce
–Microspores
–Megaspores
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Life cycle of an angiosperm,
cont.
• Microspore develops into a pollen
grain
• Megaspore develops into an
embryo sac
• Embryo sac contains seven cells
with eight nuclei
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Life cycle of an angiosperm,
cont.
• Egg cell and central cell with two
polar nuclei participate in fertilization
• Double fertilization resulting in
formation of
–Dipoid zygote
–Triploid endosperm
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Life cycle of
flowering
plants
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Phylum Magnoliophyta is divided
into two classes
• Monocots
• Dicots
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Most monocots have
• Floral parts in multiples of three
• Seeds that each contain one
cotyledon
• Nutritive tissue in their mature
seeds is endosperm
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Simple pistil
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Compound
pistil
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Most dicots have
• Floral parts in multiples of four or
five
• Seeds that each contain two
cotyledons
• Nutritive organs in their mature
seeds are the cotyledons
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolutionary adaptations of
flowering plants
• Reproduce sexually by forming
flowers
• After double fertilization, seeds
are formed within fruits
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolutionary adaptations of
flowering plants, cont.
• Flowering plants have
–Vessel elements in their xylem
–Efficient carbohydrate-conducting
sieve tube elements in their phloem
• Wind, water, insects, or animals
transfer pollen grains
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Carpel of Drimys piperita
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolution of gymnosperms
• Seed plants arose from seedless
vascular plants
• Progymnosperms were seedless
vascular plants
–Megaphylls
–“Modern” woody tissue
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolution of gymnosperms, cont.
• Progymnosperms probably gave
rise to conifers
• Progymnosperms probably gave
rise to seed ferns, too
• Seed ferns probably gave rise to
cycads and ginkgo
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolution of gymnosperms, cont.
• Evolution of gnetophytes is
unclear
• Flowering plants probably
descended from ancient
gymnosperms
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
Fossil flower
Copyright © 2005 Brooks/Cole — Thomson Learning
Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolution of gymnosperms, cont.
• Ancient gymnosperm have
–Leaves with broad, expanded blades
–Closed carpels
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Biology, Seventh Edition
CHAPTER 27 The Plant Kingdom: Seed Plants
• Evolution of gymnosperms, cont.
• Flowering plants probably dicots
• Amborella is a dicot that may be
the nearest living relative to the
ancestor of all flowering plants
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