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LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures by
Erin Barley
Kathleen Fitzpatrick
Plant Diversity I: How Plants
Colonized Land
Chapter 29
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Overview: The Greening of Earth
• For more than the first 3 billion years of Earth’shistory, the terrestrial surface was lifeless
• Cyanobacteria likely existed on land 1.2 billion
years ago• Around 500 million years ago, small plants,
fungi, and animals emerged on land
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• Since colonizing land, plants have diversified intoroughly 290,000 living species
• Land plants are defined as having terrestrial
ancestors, even though some are now aquatic
• Land plants do not include photosynthetic
protists (algae)
• Plants supply oxygen and are the ultimate
source of most food eaten by land animals
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1 m
Figure 29.1
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Concept 29.1: Land plants evolved from
green algae
• Green algae called charophytes are the closest
relatives of land plants
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Morphological and Molecular Evidence
• Many characteristics of land plants also appear ina variety of algal clades, mainly algae
• However, land plants share four key traits withonly charophytes
– Rings of cellulose-synthesizing complexes
– Peroxisome enzymes
– Structure of flagellated sperm
– Formation of a phragmoplast
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1 m
Figure 29.2
30 nm
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• Comparisons of both nuclear and chloroplastgenes point to charophytes as the closest living
relatives of land plants
• Note that land plants are not descended from
modern charophytes, but share a common
ancestor with modern charophytes
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1 m
Figure 29.3
Chara species, a pond organism
Coleochaete orb icu laris, adisk-shaped charophytethat also lives in ponds (LM)
40 m
5 mm
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1 m
Figure 29.3a
Chara species, a pond organism
5 mm
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1 m
Figure 29.3b
Coleochaete orb icular is, adisk-shaped charophyte thatlives in ponds (LM)
40 m
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Adaptations Enabling the Move to Land
• In charophytes a layer of a durable polymer calledsporopollenin prevents exposed zygotes from
drying out
• Sporopollenin is also found in plant spore walls
• The movement onto land by charophyte ancestors
provided unfiltered sun, more plentiful CO2,
nutrient-rich soil, and few herbivores or pathogens
• Land presented challenges: a scarcity of waterand lack of structural support
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• The accumulation of traits that facilitated survivalon land may have opened the way to its
colonization by plants
• Systematists are currently debating the
boundaries of the plant kingdom
• Some biologists think the plant kingdom should be
expanded to include some or all green algae
• Until this debate is resolved, we define plants asembryophytes, plants with embryos
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1 m
Figure 29.4
Red algae
Chlorophytes
Charophytes
Embryophytes
ANCESTRALALGA
V i r i d i
pl an t a e S
t r e p t o ph y t a
P l an t a e
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Derived Traits of Plants
• Four key traits appear in nearly all land plants butare absent in the charophytes
– Alternation of generations and multicellular,
dependent embryos
– Walled spores produced in sporangia
– Multicellular gametangia
– Apical meristems
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Alternation of Generations and Multicellular,Dependent Embryos
• Plants alternate between two multicellular stages,
a reproductive cycle called alternation ofgenerations
• The gametophyte is haploid and produceshaploid gametes by mitosis
• Fusion of the gametes gives rise to the diploidsporophyte, which produces haploid spores bymeiosis
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Fi 29 5
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1 m
Figure 29.5a
Gamete from
another plant
Key
Haploid (n )Diploid (2n )
Gametophyte(n )
Mitosis Mitosis
Spore Gamete
MEIOSIS FERTILIZATION
Zygote
MitosisSporophyte(2n )
Alternation of generations
2n
n
n n
n
Fi 29 5b
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1 m
Figure 29.5b
Embryo
Maternal tissue
Embryo (LM) andplacental transfer cell (TEM)
of Marchant ia (a liverwort)
Wall ingrowths
Placental transfercell (outlined inblue)
10 m
2 m
Fi 29 5b
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1 m
Figure 29.5ba
Embryo
Maternal tissue
10 m
Figure 29 5bb
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1 m
Figure 29.5bb
Wall ingrowths
Placental transfer
cell (outlined inblue)
2 m
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Walled Spores Produced in Sporangia• The sporophyte produces spores in organs called
sporangia
•
Diploid cells called sporocytes undergo meiosisto generate haploid spores
• Spore walls contain sporopollenin, which makes
them resistant to harsh environments
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Figure 29 5c
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1 m
Figure 29.5c
Spores
Sporangium
Longitudinal section ofSphagnum sporangium (LM)
Sporophyte
Gametophyte
Sporophytes and sporangia of Sphagnum (a moss)
Figure 29 5ca
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1 m
Figure 29.5ca
Sporangium
Sporophyte
Gametophyte
Sporophytes and sporangia of Sphagnum (a moss)
Figure 29 5cb
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1 m
Figure 29.5cb
Spores
Sporangium
Longitudinal section of
Sphagnum sporangium (LM)
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Multicellular Gametangia• Gametes are produced within organs called
gametangia
•
Female gametangia, called archegonia, produceeggs and are the site of fertilization
• Male gametangia, called antheridia, produce and
release sperm
© 2011 Pearson Education, Inc.
Figure 29 5d
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1 m
Figure 29.5d
Female
gametophyte
Male
gametophyte
Archegonia,each with anegg (yellow)
Antheridia
(brown),containingsperm
Archegonia and antheridia of Marchant ia (a liverwort)
Figure 29 5da
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1 m
Figure 29.5da
Female
gametophyte
Malegametophyte
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Apical Meristems• Plants sustain continual growth in their apical
meristems
•
Cells from the apical meristems differentiate intovarious tissues
© 2011 Pearson Education, Inc.
Figure 29.5e
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1 m
gu e 9 5e
Apical meristemof shoot
Developingleaves
Shoot100 m100 m
Root
Apicalmeristemof root
Apical meristems of plantroots and shoots
Figure 29.5ea
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1 m
g
100 mRoot
Apicalmeristemof root
Figure 29.5eb
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1 m
g
Apical meristemof shoot
Developingleaves
Shoot100 m
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• Additional derived traits include Cuticle, a waxy covering of the epidermis
Mycorrhizae, symbiotic associations between
fungi and land plants that may have helped plants
without true roots to obtain nutrients
Secondary compounds that deter herbivores and
parasites
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The Origin and Diversification of Plants
• Fossil evidence indicates that plants were on landat least 475 million years ago
• Fossilized spores and tissues have been extracted
from 475-million-year-old rocks
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Figure 29.6
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1 m
(a) Fossilizedspores
Fossilizedsporophytetissue
(b)
Figure 29.6a
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(a) Fossilizedspores
Figure 29.6b
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Fossilizedsporophytetissue
(b)
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•Those ancestral species gave rise to a vastdiversity of modern plants
© 2011 Pearson Education, Inc.
Figure 29.7
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1 m
Origin of land plants (about 475 mya)
Origin of vascular plants (about 425 mya)
Origin of extant seed plants (about 305 mya)
2
1
3
2
1ANCESTRALGREENALGA
500 450 400 350 300 50 0
Millions of years ago (mya)
Liverworts
Mosses
Hornworts
Lycophytes (clubmosses, spikemosses, quillworts)
Pterophytes (ferns,horsetails, whisk ferns)
Gymnosperms
Angiosperms
L an d
pl an t s
V a s c ul ar pl an t s
N onv a s c ul ar
pl an t s
( b r y o ph y t e s )
S e e d l e s s
v a s c ul ar
pl an t s
S e e d
pl an t s
3
Figure 29.7a
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1 m
Origin of land plants (about 475 mya)
Origin of vascular plants (about 425 mya)
Origin of extant seed plants (about 305 mya)
3
ANCESTRALGREENALGA
500 450 400 350 300 50 0
Millions of years ago (mya)
Liverworts
Mosses
Hornworts
Lycophytes (clubmosses, spikemosses, quillworts)
Pterophytes (ferns,horsetails, whisk ferns)
Gymnosperms
Angiosperms
2
1
1
2
3
Figure 29.7b
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1 m
Liverworts
Mosses
Hornworts
Lycophytes (clubmosses, spikemosses, quillworts)
Pterophytes (ferns,horsetails, whisk ferns)
Gymnosperms
Angiosperms
L an d
pl an t s
V a s c ul ar pl an t
s
N onv a s
c ul ar
pl an t s
( b r y o ph
y t e s )
S e e d l e s s
v a s c ul ar
pl an t s
S e e d
pl an t s
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•Land plants can be informally grouped based onthe presence or absence of vascular tissue
• Most plants have vascular tissue; these constitute
the vascular plants
• Nonvascular plants are commonly called
bryophytes
• Bryophytes are not a monophyletic group; their
relationships to each other and to vascular plantsis unresolved
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•Seedless vascular plants can be divided intoclades
– Lycophytes (club mosses and their relatives)
– Pterophytes (ferns and their relatives)
• Seedless vascular plants are paraphyletic, and are
of the same level of biological organization, or
grade
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• A seed is an embryo and nutrients surrounded bya protective coat
• Seed plants form a clade and can be divided into
further clades
– Gymnosperms, the “naked seed” plants,
including the conifers
– Angiosperms, the flowering plants
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Table 29. 1
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1 m
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Concept 29.2: Mosses and other nonvascular
plants have life cycles dominated by
gametophytes
• Bryophytes are represented today by three phylaof small herbaceous (nonwoody) plants
– Liverworts, phylum Hepatophyta
– Hornworts, phylum Anthocerophyta
– Mosses, phylum Bryophyta
•
Bryophyte refers to all nonvascular plants,whereas Bryophyta refers only to the phylum ofmosses
© 2011 Pearson Education, Inc.
Figure 29.UN01
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1 m
Nonvascular plants (bryophytes)
Seedless vascular plantsGymnosperms
Angiosperms
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Bryophyte Gametophytes
•In all three bryophyte phyla, gametophytes arelarger and longer-living than sporophytes
• Sporophytes are typically present only part of the
time
© 2011 Pearson Education, Inc.
Figure 29.8-1
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Protonemata(n )
Key
Haploid (n )
Diploid (2n )
“Bud”
“Bud”
Male
gametophyte(n )
GametophoreSporesSporedispersal
Peristome
Female
gametophyte(n ) Rhizoid
Sporangium Seta
Capsule(sporangium)
Foot
MEIOSIS
Mature sporophytes
2 m m
Capsule withperistome (LM)
Female
gametophytes
1 m
Figure 29.8-2
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Protonemata(n )
Key
Haploid (n )
Diploid (2n )
“Bud”
“Bud”
Male
gametophyte(n )
AntheridiaSperm
Egg
ArchegoniaGametophoreSpores
Sporedispersal
Peristome
Female
gametophyte(n ) Rhizoid
FERTILIZATION
(within archegonium)Sporangium Seta
Capsule(sporangium)
Foot
MEIOSIS
Mature sporophytes
2 m m
Capsule withperistome (LM)
Femalegametophytes
1 m
Figure 29.8-3
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Protonemata(n )
Key
Haploid (n )
Diploid (2n )
“Bud”
“Bud”
Male
gametophyte(n )
AntheridiaSperm
Egg
ArchegoniaGametophoreSpores
Sporedispersal
Peristome
Sporangium
Female
gametophyte(n ) Rhizoid
FERTILIZATION
(within archegonium)Zygote(2n )
Archegonium
Embryo
Seta
Capsule(sporangium)
Foot
Youngsporophyte(2n )
MEIOSIS
Mature sporophytes
2 m m
Capsule withperistome (LM)
Femalegametophytes
1 m
Figure 29.8a
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1 m
2 m
m
Capsule with peristome (LM)
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•
A spore germinates into a gametophyte composedof a protonema and gamete-producinggametophore
• The height of gametophytes is constrained by lack
of vascular tissues • Rhizoids anchor gametophytes to substrate
• Mature gametophytes produce flagellated sperm
in antheridia and an egg in each archegonium• Sperm swim through a film of water to reach and
fertilize the egg
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© 2011 Pearson Education, Inc.
Animation: Moss Life Cycle
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Bryophyte Sporophytes
•
Bryophyte sporophytes grow out of archegonia,and are the smallest and simplest sporophytes of
all extant plant groups
• A sporophyte consists of a foot, a seta (stalk),
and a sporangium, also called a capsule, whichdischarges spores through a peristome
• Hornwort and moss sporophytes have stomata for
gas exchange; liverworts do not
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Figure 29.9a
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1 m
Sporophyte
Thallus
Gametophore of
female gametophyte
Marchant ia polym orph a, a “thalloid” liverwort
Marchantiasporophyte (LM)
Foot
Seta
Capsule(sporangium)
5 0 0 m
Plagioch i la deltoid ea, a“leafy” liverwort
Figure 29.9aa
Gametophore of
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1 m
Thallus female gametophyte
Marchant ia polym orpha, a “thalloid” liverwort
Figure 29.9ab
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1 m
Marchantiasporophyte (LM)
Foot
Seta
Capsule(sporangium)
5
0 0 m
Figure 29.9ac
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1 m
Plagiochi la
deltoidea, a “leafy” liverwort
Figure 29.9b
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1 m
An Anthoceros hornwort species
Sporophyte
Gametophyte
Figure 29.9c
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1 m
Poly t r ichum commune, hairy-cap moss
Capsule
Seta
Sporophyte(a sturdyplant thattakes monthsto grow)
Gametophyte
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The Ecological and Economic Importance
of Mosses
• Mosses are capable of inhabiting diverse and
sometimes extreme environments, but are
especially common in moist forests and wetlands
• Some mosses might help retain nitrogen in the
soil
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Figure 29.10
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1 mWith moss Without moss
RESULTS
A n n u a l n i t r o g e n l o s s
( k g / h a )
6
5
4
3
2
1
0
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•
Sphagnum, or“peat moss,
” forms extensivedeposits of partially decayed organic material
known as peat
• Peat can be used as a source of fuel
• Sphagnum is an important global reservoir oforganic carbon
• Overharvesting of Sphagnum and/or a drop inwater level in peatlands could release stored CO2
to the atmosphere
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Figure 29.11b
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1 m
“Tollund Man,” a bog mummy dating from405 –100 B.C.E.
(b)
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Figure 29.UN03
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1 m
Nonvascular plants (bryophytes)
Seedless vascular plants
Gymnosperms
Angiosperms
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Origins and Traits of Vascular Plants
•
Fossils of the forerunners of vascular plants dateback about 425 million years
• These early tiny plants had independent,
branching sporophytes
• Living vascular plants are characterized by
Life cycles with dominant sporophytes
Vascular tissues called xylem and phloem
Well-developed roots and leaves
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Figure 29.12
Sporangia
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1 m
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L ife Cycles with Dominant Sporophytes •
In contrast with bryophytes, sporophytes ofseedless vascular plants are the larger generation,
as in familiar ferns
• The gametophytes are tiny plants that grow on or
below the soil surface
© 2011 Pearson Education, Inc.
Animation: Fern Life Cycle
Figure 29.13-1
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1 m
Key
Haploid (n )
Diploid (2n )
MEIOSISSporedispersal
Maturesporophyte(2n )
Fiddlehead (young leaf)
Sporangium
Sorus
Sporangium
Figure 29.13-2
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1 m
Key
Haploid (n )
Diploid (2n )
MEIOSISSporedispersal
Spore(n )
Younggametophyte
Rhizoid
Undersideof maturegametophyte(n )
Antheridium
Sperm
Archegonium
Egg
FERTILIZATION
Maturesporophyte(2n )
Fiddlehead (young leaf)
Sporangium
Sorus
Sporangium
Figure 29.13-3
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1 m
Key
Haploid (n )
Diploid (2n )
MEIOSISSporedispersal
Spore(n )
Younggametophyte
Rhizoid
Undersideof maturegametophyte(n )
Antheridium
Sperm
Archegonium
Egg
FERTILIZATIONZygote(2n )
Gametophyte
Newsporophyte
Maturesporophyte(2n )
Fiddlehead (young leaf)
Sporangium
Sorus
Sporangium
T t i X l d Phl
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Transport in Xylem and Phloem
•
Vascular plants have two types of vascular tissue:xylem and phloem
• Xylem conducts most of the water and mineralsand includes dead cells called tracheids
• Water-conducting cells are strengthened by lignin and provide structural support
• Phloem consists of living cells and distributessugars, amino acids, and other organic products
• Vascular tissue allowed for increased height,which provided an evolutionary advantage
© 2011 Pearson Education, Inc.
E l ti f R t
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Evolution of Roots •
Roots are organs that anchor vascular plants• They enable vascular plants to absorb water and
nutrients from the soil
• Roots may have evolved from subterranean stems
© 2011 Pearson Education, Inc.
E l ti f L
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Evolution of Leaves •
Leaves are organs that increase the surface areaof vascular plants, thereby capturing more solar
energy that is used for photosynthesis
• Leaves are categorized by two types
Microphylls, leaves with a single vein
Megaphylls, leaves with a highly branched
vascular system
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•
According to one model of evolution, microphyllsevolved as outgrowths of stems
• Megaphylls may have evolved as webbing
between flattened branches
© 2011 Pearson Education, Inc.
Figure 29.14
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1 m
Vascular tissue Sporangia Microphyll
(a) Microphylls (b) Megaphylls
Overtoppinggrowth
Megaphyll
Otherstemsbecomereducedandflattened.
Webbingdevelops.
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Figure 29.14b
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1 m(b) Megaphylls
Overtoppinggrowth
Megaphyll
Otherstemsbecome
reducedandflattened.
Webbingdevelops.
S h ll d S V i ti
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Sporophyl ls and Spore Variations •
Sporophylls are modified leaves with sporangia• Sori are clusters of sporangia on the undersides
of sporophylls
• Strobili are cone-like structures formed from
groups of sporophylls
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•
Most seedless vascular plants are homosporous,producing one type of spore that develops into abisexual gametophyte
• All seed plants and some seedless vascular plants
are heterosporous • Heterosporous species produce megaspores,
which give rise to female gametophytes, andmicrospores, which give rise to male
gametophytes
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Figure 29.15aa
Selaginella
moel lendorff i i ,
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moellendorff i i ,
a spike moss
1 c m
Figure 29.15ab
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1 m
Isoetes
gunni i ,a quillwort
Figure 29.15ac
2.5 cm
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1 mDiphasiastrum tr is tachyum,
a club moss
Strobili(clusters ofsporophylls)
Figure 29.15b
Athyr ium Equisetum arvense,
fi ld h il
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1 m
f i l ix-femina,
lady fern
field horsetail
Vegetative stem
Strobilus on
fertile stem
Psi lotum
nudum,
a whisk
fern
4 c m
2 5 c m
1 . 5 c m
Figure 29.15ba
Athyr ium
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1 m
Athyr ium
fi l ix-femina,
lady fern
2 5 c m
Figure 29.15bb
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1 m
Equisetum arvense,field horsetail
Vegetative stem
Strobilus on
fertile stem
1
. 5 c m
Figure 29.15bc
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1 m
Psi lo tumnudum,
a whisk
fern
4
c m
Phylum Lycophyta: Club Mosses Spike
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Phylum Lycophyta: Club Mosses, Spike
Mosses, and Quil lworts • Giant lycophytes trees thrived for millions of years
in moist swamps
• Surviving species are small herbaceous plants
• Club mosses and spike mosses have vascular
tissues and are not true mosses
© 2011 Pearson Education, Inc.
Phylum Pterophyta: Ferns Horsetai ls and
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Phylum Pterophyta: Ferns, Horsetai ls, and
Whisk Ferns and Relatives • Ferns are the most diverse seedless vascular
plants, with more than 12,000 species
• They are most diverse in the tropics but also thrive
in temperate forests
• Horsetails were diverse during the Carboniferous
period, but are now restricted to the genus
Equisetum• Whisk ferns resemble ancestral vascular plants
but are closely related to modern ferns
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The Significance of Seedless Vascular Plants
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The Significance of Seedless Vascular Plants
•
The ancestors of modern lycophytes, horsetails,and ferns grew to great heights during the
Devonian and Carboniferous, forming the first
forests
• Increased growth and photosynthesis removedCO2 from the atmosphere and may have
contributed to global cooling at the end of the
Carboniferous period
• The decaying plants of these Carboniferous
forests eventually became coal
© 2011 Pearson Education, Inc.
Fern Lycophyte trees Horsetail
Tree trunk
covered with
ll l
Lycophyte tree
reproductive
t t
Figure 29.16
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small leaves structures
1 m
Figure 29.UN02
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Figure 29.UN04
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1 m
Homosporous spore production
Heterosporous spore production
Sporangium
on sporophyllSingle
type of spore
Typically a
bisexual
gametophyte
Eggs
Sperm
Megasporangium
on megasporophyllMegaspore Female
gametophyte
Male
gametophyte
Eggs
SpermMicrosporeMicrosporangiumon microsporophyll
Gametophyte
Mitosis Mitosis
Apical meristemof shoot
Developingleaves
Figure 29.UN05
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Mitosis Mitosis
SporeGamete
MEIOSIS FERTILIZATION
Zygote
Mitosis
Sporophyte
Haploid
Diploid
Alternation of generations
4
21
3
Apical meristems
Archegonium
with egg
Antheridium
with sperm
Sporangium Spores
Multicellular gametangia Walled spores in sporangia
n
n n
n
2n
1 m
Figure 29.UN05a
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1 m
Gametophyte
Mitosis Mitosis
SporeGamete
MEIOSIS FERTILIZATION
Zygote
Mitosis
Sporophyte
Haploid
Diploid
Alternation of generations1
n
n n
n
2n
Figure 29.UN05b
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Apical meristem
of shoot
Developing
leaves
Apical meristems2
Figure 29.UN05c
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Archegoniumwith egg
Antheridiumwith sperm
Multicellular gametangia3
Figure 29.UN05d
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Sporangium Spores
Walled spores in sporangia4
Figure 29.UN06
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1 m
Figure 29.UN07
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1 m
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Figure 29.UN09
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1 m
Figure 29.UN10
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1 m
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