Plants
Green Algae
Closely related to
land plants
Charophyceae
(stoneworts)
Nonvascular
Plants
1 cm
Major
Morphological
Differences
Among Plants
Seedless
Vascular Plants
Seed
Plants
Have vascular
tissue but no
seeds (Ex. Ferns)
Have vascular tissue
& make seeds
(Ex. Pines,
Flowering plants)
5 mm
No vascular tissue to
conduct water & provide
support (Ex. mosses)
Most major
morphological
innovations:
stomata,
vascular tissue,
roots, leaves
First evidence
Extensive
of land plants:
cuticle, spores,
coal-forming
swamps
sporangia
475mya
416
359
299
Five Major Events in
Plant Diversification
Both wet and dry
environments
blanketed with
green plants for
the first time
Diversification
of flowering
plants
145
Five time intervals encompass the five
major events in plant diversification
Present
Glaucophyta (glaucophyte algae)
PLANTAE
Rhodophyta (red algae)
GREEN ALGAE
Chloroplasts containing
chlorophyll a + b
and b-carotene
GREEN PLANTS
Ulvophyceae (ulvophytes)
Coleochaetophyceae (coleochaetes)
Charophyceae (stoneworts)
Common ancestor
to all green plants
NONVASCULAR PLANTS
LAND PLANTS
Hepaticophyta (liverworts)
Bryophyta (mosses)
Ability to live on land
Anthocerophyta (hornworts)
SEEDLESS PLANTS
Bacteria
Archaea
Lycophyta (lycophytes)
Psilotophyta (whisk ferns)
Eukarya
PLANTAE
VASCULAR PLANTS
Pteridophyta (ferns)
Vascular
tissue
Equisetophyta (horsetails)
GYMNOSPERMS SEED PLANTS
Ginkgophyta (ginkgo)
Molecular
Phylogenies
of Plants
Cycadophyta (cycads)
Cupressophyta (redwoods et al.)
Pinophyta (pines et al.)
Seeds
Gnetophyta (gnetophytes)
ANGIOSPERMS
Anthophyta (angiosperms)
Preventing Water Loss: Cuticle & Stomata
Leaf cross section
Cuticle is a waxy layer that prevents
water loss from stems & leaves
Cuticle
Moist
photosynthetic
cells
Stomata have pores that allow gas
exchange in photosynthetic tissues
Pore
Guard cell
Cuticle
25 µm
Stoma
Cuticle & stomata are the most fundamental plant
adaptations to life on land
Upright Growth & Water Transport:
Vascular Tissue
Simple waterconducting cells
Primary
wall
(with
cellulose)
First
vascular
tissue
Ends have
pits in
secondary
cell wall
(inside)
Primary wall
(with cellulose)
Primary wall
(with cellulose)
Lignin
Tracheids
Secondary wall
(with lignin)
Vessel
elements
Ends have gaps
through primary
& secondary cell
walls
Primary wall
(with cellulose)
Secondary wall
(with lignin)
Elongated cells
with little
structural support
Some
structural
support
Increased
structural
support
Found in fossils &
present-day mosses
Found in
fossils
Found in all
vascular plants
Found in
gnetophytes
& angiosperms
Red algae
GREEN ALGAE
Ulvophytes
Stoneworts
NONVASCULAR PLANTS
Liverworts
Mosses
Cuticle, pores
Most key
innovations
for living on
land evolved
only once
Hornworts
Stomata
SEEDLESS VASCULAR PLANTS
Early vascular plants
Lycophytes
Vascular
tissue
Roots,
tracheids
True
leaves
Vessel elements
evolved more
than once
Whisk ferns
Ferns
Horsetails
GYMNOSPERMS
Ginkgo
Cycads
Redwoods et al.
Pines et al.
Wood
Vessel elements
Vessel elements
Gnetophytes
ANGIOSPERMS
Angiosperms
LAND PLANTS
A Series of
Evolutionary
Innovations
Allowed
Plants to
Adapt to
Life on Land
Coleochaetes
Spores or
zygotes encased
in tough coat of
sporopollenin
Reproduction in Dry Conditions
Producing Gametes in Protected Structures
Male
Moss gametophytes are
either male or female
Female
Antheridia
(containing sperm)
Eggs
0.2 mm
Archegonia
In all land plant groups but Angiosperms,
gametes are produced in gametangia
0.2 mm
Alternation of Generations
M
Haploid (n)
Diploid (2n)
SIS
O
I
E
M
ITO
Spores (n)
(2n)
Gametophyte
(multicellular,
haploid)
Sporophyte
(multicellular,
diploid)
M
IT
O
SIS
MITOSIS
Zygote
(2n)
Gametes
(n)
M
SIS
FERTILIZATION
IT
IS
S
O
(n)
Gametophyte-Dominant to
Sporophyte-Dominant Trend in Life Cycles
Haploid (n)
MITOSIS
Mature
sporophyte
(2n)
SIS
O
I
ME
Spores dispersed
by wind (n)
MITOSIS
MIT
OSI
S
Developing
gametophytes (n)
Sperm
swim to
egg
Developing
sporophyte
(2n)
Mature
female
gametophyte
(n)
Zygote
(2n)
MIT
OSI
S
Diploid (2n)
Egg
(n)
Sperm 2 µm
develop in
antheridia
2 µm
Mature female
FERTILIZATION Eggs develop gametophyte
in archegonia
(n)
Archegonium
Mature male
gametophyte
(n)
The gametophyte-dominant life cycle evolved early
and occurs in today’s mosses
Gametophyte-Dominant to
Sporophyte-Dominant Trend in Life Cycles
Haploid (n)
MITOSIS
S
SI
O
EI
M
MIT
OS
IS
Spores
dispersed
by wind (n)
Developing
gametophyte (n)
Spores are
produced in
sporangia
1 mm
Sporophyte
(2n)
M
IT
OS
IS
Diploid (2n)
Mature
gametophyte
(n; underside)
Sperm
develop
in antheridia
Zygote
(2n)
Sperm
swim to egg
Egg (n)
Mature
sporophyte (2n)
Gametophyte
(n; side view)
FERTILIZATION
Archegonium
Eggs develop
in archegonia
The sporophyte-dominant life cycles evolved
later in lineages such as ferns
Homosporous & Heterosporous Plants
Nonvascular plants and most seedless
vascular plants are homosporous
Seed plants are heterosporous
Seeds
Embryo
Nutritive tissue
Protective coat
Seeds contain an embryo and a food supply
and can be dispersed
Gametophyte-Dominant to
Sporophyte-Dominant Trend in Life Cycles
SIS
MEIO
Haploid (n)
Diploid (2n)
Cones with
microsporangia
Pollen grains
disperse via wind
MITOSIS
Microspore (n)
forms pollen grain
Pollen grain
(male gametophyte)
PO
LL
IN
AT
IO
N
Megasporangium
Mother
cell (2n)
S
MEIOSI
Ovulate cone
Ovules (contain
megasporangia)
Embryo
(2n)
Mature
sporophyte (2n)
Developing
sporophyte
Seeds (disperse
via wind or animals)
Female
gametophyte (n)
Egg (n)
Pollen tube
ION
AT
Z
I
TIL SIS Pollen tube
delivers sperm
FER MITO
to egg
The heterosporous, sporophyte-dominant
life cycle of gymnosperms
Four meiotic
products; one is
large and forms
the megaspore
(n)
Three meiotic
products die
Pollen grain
Megaspore divides
to form female
gametophyte (n),
which forms eggs
by mitosis. (Only
one egg is fertilized
and develops.)
Gametophyte-Dominant to SporophyteDominant Trend in Life Cycles
Pollen grains disperse
via wind or animals
MITOSIS
SIS
MEIO
Haploid (n)
Diploid (2n)
Microspore (n)
forms pollen grain
Anther
Top of
stamen
Ovule
Pollen grain
(male
gametophyte)
PO L
LIN
AT
ION
Sperm travel
down growing
pollen tube to
reach egg
MITOSIS
MEIOSIS
Ovary
Pollen lands
near female
gametophyte;
produces
pollen tube
and sperm
Egg (n)
Megaspore
(n: retained
in ovary)
Embryo
(2n)
Endosperm (3n)
forms nutritive
tissue in seed
Nutritive
tissue
(3n)
Mature
sporophyte
(2n)
Developing
sporophyte
(2n)
O
MIT
Seed (disperses
via wind or animals)
FE DO
RT UB
ILI LE
ZA
TIO
N
Bottom of
carpel
Megasporangium
Female gametophyte
(n: retained in ovary)
SIS
Zygote
(2n)
Fruit (develops from ovary
wall) containing seed
The heterosporous, sporophyte-dominant
life cycle of angiosperms