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2/9/11
Plants
•  Key point: History of land plants is the
increasing adaptation to terrestriality.
•  Colonized land 475 mya (Ordovician),
began growing taller 370 mya
(Carboniferous).
•  Plants form the basis for every
terrestrial ecosystem.
Challenges of terrestriality
•  Dessication:
medium of air, not
water.
•  Access to water,
nutrients.
•  Reproductive
strategies.
Advantages of terrestriality
•  Ample, unfiltered
sunlight
•  Abundant CO2
•  Abundant soil
nutrients
•  Initially no natural
enemies
(herbivores)
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Important adaptations to life
on land
•  Waxy cuticle
•  Gametangia and
protected embryo
•  Roots (below) stems
(above)
•  Leaves, stomata:
photosynthesis
Origins: Charophyte Green Algae
EVIDENCE
•  Homologous chloroplasts
•  Biochemical similarity: cellulose in cell wall
•  Similarity in mitosis, cytokinesis
•  Similarity in sperm ultrastructure
•  Genetic relationship: some nuclear genes,
ribosomal RNA
Origins: Charophyte Green Algae
ESSENTIAL DIFFERENCES
Green Algae
Plants
Medium: water (whole alga
has access)
Medium: air, nonsupportive (roots, stiff
stem, cuticle)
Photosynthesis in most
cells (light limited)
Photosynthesis in aerial
parts (leaves, stomata)
Reproduction mostly
asexual
Reproduction sexual:
gametangia, embryo
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Major events in plant evolution
A. 
B. 
C. 
D. 
Changes in life history
Vascular tissue
Seeds
Flowering plants
Major events in plant evolution
A. Changes in life history
“The changes that affect an organism’s
schedule of reproduction and survival.”
1.  Alternation of generations
–  Evolved independently in fungi, cellular
slime molds, brown algae, red algae, and
green algae.
Generalized Alternation of
Generation in Plants
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Major events in plant evolution
A. Changes in life history
2.  Generations are heteromorphic.
3.  Shift of dominance from gametophyte (n) to
sporophyte (2n).
4.  Replacement of flagellated sperm by pollen.
B. Vascular tissue
•  Cells joined into
conducting tubes.
•  Xylem: dead, lignified
tubes conduct water,
mineral from roots
upward.
•  Phloem: living tubes
conduct sugar, amino
acids from photosythetic
parts downward.
C. Seeds
•  An embryo
packed with
food.
•  First seeds
unencapsulated
Gymnosperms.
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D. Flowering Plants:
Angiosperms
•  Complex structure
containing seeds
within protective
ovary.
•  Most diverse
(species) plant
group.
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Embryo: zygotes are
retained within tissues of
the female parent plant.
All descendants known
as “Embryophyta”
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Vascular tissue: Cells joined
into tubes to transport water
and soil nutrients upward
(xylem) and carbohydrates
downward (phloem). All
descendants known as
“Tracheophytes”
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Flowers:
Complex
structure
containing seeds
within protective
ovary. All
descendants
known as
“Angiosperms”
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Seeds: Embryo
packed with a supply
of nutrients inside a
protective coat. All
descendants known
as “Spermatophytes”
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Increasing
Terrestriality
Key point: History of land plants is the increasing adaptation to terrestriality.
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BRYOPHYTES
Mosses, Liverworts, Hornworts
KEY POINTS
•  Gametophyte dominant
•  No vascular tissue
•  Ancient but persistent group.
BRYOPHYTES
Mosses, Liverworts, Hornworts
•  Not monophyletic (???)
•  Date to > 475 mya
•  Very successful, 24,000
species, but never
dominated landscape.
•  Non-vascular; therefore
only found in moist
environments.
•  Need water for sperm
transport and absorption.
Fig. 29.7 from textbook indicates
that bryophytes are paraphyletic,
however…
BRYOPHYTES
Mosses, Liverworts, Hornworts
•  Not monophyletic (???)
•  Date to > 475 mya
•  Very successful, 24,000
species, but never
dominated landscape.
•  Non-vascular; therefore
only found in moist
environments.
•  Need water for sperm
transport and
absorption.
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Bryophytes
Common Characteristics
•  Gametophyte generation
dominates
•  Lack stiff, supporting
structures
–  Therefore low-growing
•  Separate male and female
gametophyte
–  Male gametangium =
antheridium (flagellated
sperm cells)
–  Female gametangium =
archegonium (single egg)
•  Fertilization within
archegonium -> zygote ->
embryo
Bryophytes
Common Characteristics
•  Gametophyte generation
dominates
•  Lack stiff, supporting
structures
–  Therefore low-growing
•  Separate male and female
gametophyte
–  Male gametangium =
antheridium (flagellated
sperm cells)
–  Female gametangium =
archegonium (single egg)
•  Fertilization within
archegonium -> zygote ->
embryo
Bryophytes
Common Characteristics
•  Gametophyte generation
dominates
•  Lack stiff, supporting
structures
–  Therefore low-growing
•  Separate male and female
gametophyte
–  Male gametangium =
antheridium (flagellated
sperm cells)
–  Female gametangium =
archegonium (single egg)
•  Fertilization within
archegonium  zygote 
embryo
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Bryophytes
Bryophyta: Mosses
•  Best known of bryophytes
–  Note that “bryophytes” is a term
of convenience, where as
Bryophyta is restricted to the
mosses.
•  Small individual plants in tight
packages--form
spongy,supporting mats.
•  Anchor to substrate with rhizoids
–  “roots”, like “leaves” not
homologous with vascular plants
•  Life cycle good example of
alternating generations
Fig. 29-8-3
Bryophytes
Raindrop
Sperm
“Bud”
Male
gametophyte
(n)
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
Antheridia
“Bud”
Egg
Spores
Gametophore
Female Archegonia
gametophyte (n)
Spore
dispersal
Rhizoid
Peristome
FERTILIZATION
Sporangium
MEIOSIS
Mature
sporophytes
Seta
Capsule
(sporangium)
Foot
Zygote
(2n)
(within archegonium)
Embryo
2 mm
Archegonium
Capsule with
peristome (SEM)
Young
sporophyte
(2n)
Female
gametophytes
Bryophytes
Hepatophyta: Liverworts
•  Very inconspicuous,
lobed bodies
hugging ground
•  Life cycle like
mosses
•  Thalloid form &
Leafy form
•  Likely sister-group of
remaining (all other)
Plantae
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Bryophytes
Anthocerophyta: Hornworts
•  Resemble liverworts
•  Name derives from
sporophytes in hornlike capsules of
matlike gametophyte
•  Cells have a single
large chloroplast
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Vascular tissue: Cells joined
into tubes to transport water
and soil nutrients upward
(xylem) and carbohydrates
downward (phloem). All
descendants known as
“Tracheophytes”
Seedless Vascular Plants
Lycophytes & Pterophytes
KEY POINTS
•  Plants with xylem and phloem
•  Branched sporophyte dominates
•  Ancestral state retains flagellated sperm
and thus inhabit moist environments
•  Paraphyletic
•  “Vascular plant” monophyletic:
Tracheophyta.
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Seedless Vascular Plants
General
Macroevolution
Lycopod with
microphylls
shown
•  Earliest are found in
mid-Paleozoic, 425 mya
(e.g. Cooksonia)
•  Dominated landscape
by end of paleozoic
•  Branched sporophyte
dominant generation
•  All with flagellated
sperm
Fern with
characteristic
macrophylls
Fern sperm
with multiple
flagellae
Seedless Vascular Plants
General
Structure
•  Roots & shoots
•  Lignified vascular
tissue: Xylem, Phloem
•  Some heterosporous
–  Megaspores (female)
–  Microspores (male)
–  As in seed plants
Megaspores
Microspores
Lycopod Selaginella
Seedless Vascular Plants
Lycophyta: Lycopods
Club mosses, quillworts, ground pines
•  Relicts of flourishing past,
two lineages:
–  Giant, tree-like, woody
–  Small herbaceous
•  Only small forms extant
–  E.g. Lycopodium,
Saleginella
•  Many are tropical epiphytes;
temperate forms grow at
ground level
•  Sporangia borne on
sporophylls: leaves
specialized for reproduction
Lycopodium
Club moss or ground pine
Isoetes
Quillwort
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Seedless Vascular Plants
Lycophyta: Lycopods
Club mosses, quillworts, ground pines
• 
Relicts of flourishing past, two
lineages:
–  Giant, tree-like, woody
–  Small herbaceous
• 
Only small forms extant
• 
Many are tropical epiphytes;
temperate forms grow at ground
level
Sporangia borne on
sporophylls:
–  E.g. Lycopodium, Saleginella
• 
–  leaves specialized for
reproduction
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Note Pterophyta are sister
to Spermatophyta:
Megaphyll leaves, roots
that can branch
Seedless Vascular Plants
Pterophyta I: Horsetails
•  Previously considered own
phylum, Sphenophyta, now
placed within Pterophyta.
•  Late Paleozoic forms grew to
15m
•  Today only the genus
Equisetum
–  15 species mostly northern
hemisphere
•  Conspicuous horsetail
sporophyte
•  Homosporous…bisexual
gametophyte
An exception:
Equisetum giganteum
from Chile
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Seedless Vascular Plants
Pterophyta I: Horsetails
•  Underground rhizome
from which stems arise
•  Stems: hollow, jointed
with whorls of small
branches
•  Cone-like sporangia at
tip of stem.
Seedless Vascular Plants
Pterophyta II: True ferns
•  Most diverse seedless
vascular plants
•  Today ~12,000 species
•  Most diversity in tropics, also
common in temperate
regions.
•  Fronds are large leaves with
branched veins: megaphyll
•  Compound leaflets grow from
fiddlehead tip
•  Leaves may sprout directly
from prostrate stems
(rhizomes); or as upright
treeferns
LIFE CYCLE: sporophyte with specialized leaves, each with
clustered sporangia below (sori) which launch spores, grow
into gametophyte
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Pterophyta II: Whiskferns
•  Previously considered own
phylum, Psilophyta, now
placed within Pterophyta.
•  Simple plants.
•  Diploid sporophyte has
dichotomous branches (like
primitive Cooksonia)
•  True roots and leaves are
absent
–  Like Lycopods! However,
these have been
secondarily lost.
The
CARBONIFEROUS
• 
• 
• 
• 
360-300 mya
Height of seedless vascular
diversity and ecological
dominance.
Formed first forests.
Eventually become COAL:
–  Dead plants did not completely
decay.
–  Became peat bogs.
–  Eventually covered by sea.
–  Heat and pressure from
sediments converted peat to
coal.
4 square miles of Carboniferous coal forest in Pennsylvania
(see http://www.mnh.si.edu/highlight/riola/ for highlights)
Gymnosperms
and the Evolution of Seed Plants
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Seed Plants
Key points
•  Seed replaces spore
•  Fertilization by pollen instead of sperm
•  Two groups: gymnosperms
–  (naked seeds)
•  Angiosperms
–  (protected seeds)
Gymnosperms: Conifers & Allies
1.  Success marked by change in life
cycle
2.  Evolution
3.  Four divisions
Changes in Life Cycle
1.  Gametophyte
highly reduced
–  Retained within
reproductive tissue
of sporophyte and
not cast out as
independent
generation.
–  Shift toward
diploidy.
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Changes in Life Cycle
2.  Fertilization by
pollen rather than
swimming sperm.
–  There is no longer a
reliance on water!
Changes in Life Cycle
3. 
Seed.
– 
– 
– 
Zygote not independent
Zygote to embryo
packaged with food in a
seed coat.
Seed is “naked” born on
scales of cones.
• 
• 
Protects from
dessication.
Increases dispersal
capabilities: replaces
spore as dispersal agent.
Fig. 30-6-1
Key
Haploid (n)
Diploid (2n)
Ovulate
cone
Pollen
cone
Mature
sporophyte
(2n)
Microsporocytes
(2n)
Pollen
grains (n)
MEIOSIS
Microsporangia
Microsporangium (2n)
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Fig. 30-6-4
Key
Haploid (n)
Diploid (2n)
Ovule
Ovulate
cone
Pollen
cone
Integument
Megasporocyte (2n)
Microsporocytes
(2n)
Megasporangium
Pollen (2n)
Pollen grain
grains (n) MEIOSIS
MEIOSIS
Mature
sporophyte
(2n)
Microsporangia
Microsporangium (2n)
Surviving
megaspore (n)
Seedling
Archegonium
Female
gametophyte
Seeds
Food
reserves
(n)
Seed coat
(2n)
Embryo
(2n)
Sperm
nucleus (n)
Pollen
tube
FERTILIZATION
Egg nucleus (n)
Evolution
•  Appear much earlier than
Angiosperms, in Devonian.
“Modern” gymnosperms by
early-mid Mesozoic
•  Permian marks end of
Paleozoic.
•  Mesozoic: Age of Dinosaurs
(zoologists); Age of
Gymnosperms (botanists)
Permian harshness
(formation of Pangea)
Interior aridity
Demise of
Carboniferous forests
Mass Extinctions
Rise of Gymnosperms
Four Divisions
•  Cycadophyta
–  Cycads
•  Ginkgophyta
–  Ginkgo
•  Gnetophyta
–  Gnetales
•  Coniferophyta
–  Conifers
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Cycadophyta: Cycads
•  Cycads or “Sago” palm
•  Currently ~130 species
–  Slow-growing, tropical & subtropical
•  Flourished in Mesozoic
•  Massive cone-shaped structures bearing pollen or
ovules
•  Primarily insect pollinated, some wind pollinated.
•  Seeds eaten in Asia after removing Alkaloids
Ginkgophyta: Gingko
•  Diverse in Mesozoic, single species today
•  Known only from fossils until discovered growing in
Chinese Buddhist temples
•  Fan-shaped, deciduous leaves
•  Male trees widely planted landscape tree
–  Resistant to drought, pollution, pests
•  Seeds of female produce stench when crushed
Gnetophyta
•  Gnetum: tropical tree/vine.
•  Ephedra: Mormon or Mexican tea of American
deserts, jointed stem.
•  Welwitschia: Largest known leaves, deserts of SW
Africa, deep root, exposed leaves.
•  Fossils from Permian, but peak diversity in
Cretaceous.
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Gnetophyta
• 
Have vessel elements: Differ
from all other Gymnosperms,
share this with Angiosperms.
• 
What are the implications if
Gymnosperms are
monophyletic?
• 
What are the implications if
vessel elements are
homologous?
Coniferophyta (or Pinophyta):
Conifers
•  Pines, firs, spruce, larches,
cedars, hemlocks, (all
Pinaceae), yews, cypress,
redwoods, hoop pines,
umbrella pines, yellowwoods, plum-yews.
•  ~600 species, dominate vast
regions of taiga: northern
and southern evergreen
forests.
Coniferophyta (or
Pinophyta): Conifers
• 
• 
• 
• 
• 
• 
Evergreen, even perform limited
photosynthesis year round.
Needles are leaves
Commercially important as
timber
Tallest plant: coastal redwood
(>110m)
Heaviest plant: giant sequoia
(2500 metric tons)
Oldest plant: Bristlecone pine
>4600 years old
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Summary: Gymnosperms
•  Monophyletic sister group to
angiosperms.
•  Peak diversity in the Mesozoic, still
ecologically dominant in some
ecosystems.
•  Evolution of seed and pollen key
transitions (shared with Angiosperms)
Angiosperms
Structure & Classification
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Flowers:
Complex
structure
containing seeds
within protective
ovary. All
descendants
known as
“Angiosperms”
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KEY POINT
•  Flower and fruit as
defining
reproductive
strategy
General Aspects
Angiosperms
•  Anthophyta: “flower
plant”
•  270,000 described
species.
–  Compare this to
~900 species of
Gymnosperms!
General Aspects
Angiosperms
•  Refined vascular tissue
•  Vessel elements
present in xylem
–  shorter, wider cells
placed end to end
–  perforation plates at
end of each cell
–  line up end-to-end to
create vessels
•  Specialized for
transport, less for
support
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General Aspects
Angiosperms
•  Vessel elements
•  Also present in
Gnetales and absent
from many basal
angiosperm groups.
•  ??? Possibilities ???
General Aspects
Angiosperms
•  Of course…
•  Characterized by
flowers
•  Characterized by fleshy
ovary protecting seed
Morphology
Two Systems
•  Roots: below-ground
non-photosynthetic
–  Anchor
–  Absorption
–  Storage
•  Aerial shoots: aboveground photosynthetic
and/or transport
–  Leaves
–  Stems
•  These are
interdependent
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Morphology
Roots
Anchor Shoot System
•  Tap root
–  Single large verticle root
with secondary rootlets
–  Firm anchor
–  Food storage used by
plant when producing
flower, fruit (harvest
before flowering)
•  Fibrous root
–  Mat-like and psreading,
shallow, wide coverage
–  Grasses (good erosion
control)
Morphology
Roots
Anchor Shoot System
•  Tap root
–  Single large verticle root
with secondary rootlets
–  Firm anchor
–  Food storage used by
plant when producing
flower, fruit (harvest
before flowering)
•  Fibrous root
–  Mat-like and spreading,
shallow, wide coverage
–  Grasses (good erosion
control)
Morphology
Roots
Anchor Shoot System
•  Root hairs: For
absorption at root tip
•  Adventitious roots:
above ground roots help
support stem
–  Adventitious = Name for
any plant part growing in
abnormal place
–  Prop roots
–  Aerial roots
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Morphology
Roots
Anchor Shoot System
•  Root hairs: For
absorption at root tip
•  Adventitious roots:
above ground roots help
support stem
–  Adventitious = Name for
any plant part growing in
abnormal place
–  Prop roots
–  Aerial roots
Morphology
Shoots
Stems, leaves, flowers
• 
• 
• 
• 
• 
Nodes
Internodes
Axillary buds
Apex = terminal bud
Apical dominance
Morphology
Shoots
Stems, leaves, flowers
•  Modified stems
•  Stolons
–  Horizontal above-ground
runners (e.g.
strawberries)
•  Rhizomes
–  Horizontal below-ground
stems (potatoes, iris)
•  Bulbs
–  Vertical below ground
with leaves modified for
storage.
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Morphology
Shoots
Stems, leaves, flowers
•  Modified stems
•  Stolons
–  Horizontal above-ground
runners (e.g.
strawberries)
•  Rhizomes
–  Horizontal below-ground
stems (potatoes, iris)
•  Bulbs
–  Vertical below ground
with leaves modified for
storage.
Morphology
Shoots
Stems, leaves, flowers
•  Modified stems
•  Stolons
–  Horizontal above-ground
runners (e.g.
strawberries)
•  Rhizomes
–  Horizontal below-ground
stems (potatoes, iris)
•  Bulbs
–  Vertical below ground
with leaves modified for
storage.
Morphology
Shoots
Stems, leaves, flowers
•  Primary photosynthetic
part of plant (usually)
•  Part 1: Blade
•  Part 2: Petiole
–  Absent in many grasses
and relatives (monocots)
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Morphology
Shoots
Stems, leaves, flowers
•  Primary photosynthetic
part of plant (usually)
•  Part 1: Blade
•  Part 2: Petiole
–  Absent in many grasses
and relatives (monocots)
Morphology
Shoots
Stems, leaves, flowers
•  Highly variable
–  Within individuals
–  Between species
–  Between deeper
clades
• 
• 
• 
• 
• 
Shape
Arrangement
Margins
Venation
Simple vs
Compound
Morphology
Shoots
Stems, leaves, flowers
•  Highly variable
–  Within individuals
–  Between species
–  Between deeper
clades
• 
• 
• 
• 
• 
Shape
Arrangement
Margins
Venation
Simple vs
Compound
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Morphology
Shoots
Stems, leaves, flowers
•  Highly variable
–  Within individuals
–  Between species
–  Between deeper
clades
• 
• 
• 
• 
• 
Shape
Arrangement
Margins
Venation
Simple vs
Compound
Morphology
Shoots
Stems, leaves, flowers
•  Highly variable
–  Within individuals
–  Between species
–  Between deeper
clades
• 
• 
• 
• 
• 
Shape
Arrangement
Margins
Venation
Simple vs
Compound
Morphology
Shoots
Stems, leaves, flowers
•  Highly variable
–  Within individuals
–  Between species
–  Between deeper
clades
• 
• 
• 
• 
• 
Shape
Arrangement
Margins
Venation
Simple vs
Compound
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Morphology
Shoots
Stems, leaves, flowers
•  Some can be
highly modified:
–  Tendrils
–  Spines
–  Storage
–  Asexual
reproduction
–  Bracts
–  Insectivory
Morphology
Shoots
Stems, leaves, flowers
•  Some can be
highly modified:
–  Tendrils
–  Spines
–  Storage
–  Asexual
reproduction
–  Bracts
–  Insectivory
Morphology
Shoots
Stems, leaves, flowers
•  Some can be
highly modified:
–  Tendrils
–  Spines
–  Storage
–  Asexual
reproduction
–  Bracts
–  Insectivory
Venus flytrap
Sundew
Pitcher plant
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Morphology
Shoots
Stems, leaves, flowers
•  Angiosperm structure
specialized for sexual
reproduction.
•  Specialized shoot
made up of (usually)
four rings of modified
leaves (floral organs):
– 
– 
– 
– 
Sepals
Petals
Carpels: Female
Anthers: Male
Morphology
Shoots
Stems, leaves, flowers
•  Carpels are the
female organs
–  Ovules contain
megasporangium
–  Stigma receives
pollen
–  Style leads from
stigma to ovary
–  Ovary contains
ovules
Morphology
Shoots
Stems, leaves, flowers
•  Stamens are the
male organs
–  Filament is the
stalk
–  Anther houses
microsporangia
and produces
pollen.
–  Pollen will contain
male gametophyte
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Morphology
Shoots
Stems, leaves, flowers
•  Perfect flowers
contain both carpels
and stamens
•  Imperfect flowers
contain either carpels
or stamens
–  Monoecious: having
separate male and
female flowers on the
same plant.
–  Dioecious: having
separate male and
female plants.
Morphology
Shoots
Stems, leaves, flowers
Evolutionary Trends
1.  Reduction in number
of floral parts
2.  Floral parts fused,
compound carpels to
single and large
3.  From radial to
bilateral symmetry
4.  Ovary drops below
petals and sepals
(“inferior” ovary)
Water lily, Nymphaceae, showing
plesiomorphic state
Orchid,
showing
derived
state
Morphology
Shoots
Stems, leaves, flowers
Evolutionary Trends
1.  Reduction in number
of floral parts
2.  Floral parts fused,
compound carpels to
single and large
3.  From radial to
bilateral symmetry
4.  Ovary drops below
petals and sepals
(“inferior” ovary)
Water lily, Nymphaceae, showing
plesiomorphic state
Morning
glory,
showing
derived
state
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2/9/11
Morphology
Shoots
Stems, leaves, flowers
Evolutionary Trends
1.  Reduction in number
of floral parts
2.  Floral parts fused,
compound carpels to
single and large
3.  From radial to
bilateral symmetry
4.  Ovary drops below
petals and sepals
(“inferior” ovary)
Water lily, Nymphaceae, showing
plesiomorphic state
Pea flower,
showing
derived
state
Morphology
Shoots
Stems, leaves, flowers
Evolutionary Trends
1.  Reduction in number
of floral parts
2.  Floral parts fused,
compound carpels to
single and large
3.  From radial to
bilateral symmetry
4.  Ovary drops below
petals and sepals
(“inferior” ovary)
Major Angiosperm
Dichotomy
•  Monocots and
Dicots
•  Refers to numbers
of “seed leaves” or
cotyledons.
•  Monocots are
monophyletic.
•  Dicots are NOT.
Monocots: Grasses,
lilies, palms, etc.
Dicots:
Everything
else
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2/9/11
Major Angiosperm Dichotomy
•  Monocots and
Dicots
•  Refers to numbers
of “seed leaves” or
cotyledons.
•  Monocots are
monophyletic.
•  Dicots are NOT.
Major Angiosperm
Dichotomy
•  Monocots and
Dicots
•  Refers to numbers
of “seed leaves” or
cotyledons.
•  Monocots are
monophyletic.
•  Dicots are NOT.
Major Angiosperm
Dichotomy
•  Monocots and Dicots
•  Refers to numbers of
“seed leaves” or
cotyledons.
•  Monocots are
monophyletic.
•  Dicots are NOT.
•  “Dicot is a term of
convenience.
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Dicots &
Monocots
•  But it is a useful
distinction…
Dicots &
Monocots
•  But it is a useful
distinction…
Dicots &
Monocots
•  Discussion question:
•  For these traits, which
are plesiomorphic and
which are apomorphic?
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2/9/11
Life Forms
•  Plant forms have evolved to
fill numerous ecological roles
or “niches”.
•  Developmental plasticity
and Indeterminate growth
allow individuals to fit
particular ecological
conditions.
•  Why is this so important to a
plant?
Life Forms
•  Grasses
– 
– 
– 
– 
• 
• 
• 
• 
• 
• 
• 
Monocots
No petiole
Limited branching
No woody tissue
(herbaceous)
Forbs
Shrubs
Trees
Epiphytes
Aquatic
Herbaceous
Woody
Life Forms
•  Grasses
•  Forbs
–  Dicots
–  Generally wildflowers
–  Herbaceous
• 
• 
• 
• 
• 
• 
Shrubs
Trees
Epiphytes
Aquatic
Herbaceous
Woody
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2/9/11
Life Forms
•  Grasses
•  Forbs
•  Shrubs
–  Woody tissue
–  No distinct single trunk
• 
• 
• 
• 
• 
Trees
Epiphytes
Aquatic
Herbaceous
Woody
Life Forms
• 
• 
• 
• 
Grasses
Forbs
Shrubs
Trees
–  Woody tissue
–  Single main trunk
–  Apical dominance
pronounced
• 
• 
• 
• 
Epiphytes
Aquatic
Herbaceous
Woody
Life Forms
• 
• 
• 
• 
Grasses
Forbs
Shrubs
Trees
–  Woody tissue
–  Single main trunk
–  Apical dominance
pronounced
• 
• 
• 
• 
Epiphytes
Aquatic
Herbaceous
Woody
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2/9/11
Life Forms
• 
• 
• 
• 
• 
Grasses
Forbs
Shrubs
Trees
Epiphytes
–  Plant that grows on
another plant
•  Aquatic
•  Herbaceous
•  Woody
Life Forms
• 
• 
• 
• 
• 
• 
Grasses
Forbs
Shrubs
Trees
Epiphytes
Aquatic
–  Numerous adaptations for
living in water
•  Herbaceous
•  Woody
Life Forms
• 
• 
• 
• 
• 
• 
• 
Grasses
Forbs
Shrubs
Trees
Epiphytes
Aquatic
Herbaceous
–  Die down each year.
–  Can be annual to
perennial.
–  No structural lignin
•  Woody
–  Perennial and persistent
–  Structural lignin (wood)
•  Dichotomy used in above
distinctions.
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Summary
•  Flowering plants have been very
successful: innovation of flower & fruit.
•  Diverse morphology structured around
the root system and the shoot system.
•  Developmental plasticity and evolution
of different life forms important in
colonization of novel ecological niches.
37