Non-Vascular Plants and
Ferns
Evolution of Land Plants
• Land plants evolved
from green algae
• The green algae called
charophyceans are the
closest relatives of
land plants
• Comparisons of both
nuclear and
chloroplast genes
– Point to charophyceans
as the closest living
relatives of land plants
Chara,
a pond
organism
(a)
10 mm
Coleochaete orbicularis, a disk-
shaped charophycean (LM)
(b)
40 µm
Origin and Diversification of
Plants
• Fossil evidence
indicates that plants
were on land at
least 475 million
years ago
• Whatever the age of
the first land plants
those ancestral
species gave rise to
a vast diversity of
modern plants
Plant Evolution
Bryophytes
(nonvascular plants)
Seedless vascular plants
Seed plants
Vascular plants
Land plants
Origin of seed plants
(about 360 mya)
Origin of vascular
plants (about 420 mya)
Origin of land plants
(about 475 mya)
Ancestral
green alga
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Bryophytes
• Life cycles of mosses and other
bryophytes are dominated by the
gametophyte stage
• Bryophytes are represented today by
three phyla of small herbaceous
(nonwoody) plants
– Liverworts, phylum Hepatophyta
– Hornworts, phylum Anthocerophyta
– Mosses, phylum Bryophyta
Bryophytes
LIVERWORTS (PHYLUM HEPATOPHYTA)
HORNWORTS (PHYLUM ANTHOCEROPHYTA)
MOSSES (PHYLUM BRYOPHYTA)
Gametophore of
female gametophyte
Marchantia polymorpha,
a “thalloid” liverwort
Foot
Sporangium
Seta
5
0
0
µ
m
Marchantia sporophyte (LM)
Plagiochila
deltoidea,
a “leafy”
liverwort
An Anthoceros
hornwort species
Sporophyte
Gametophyte
Polytrichum commune,
hairy-cap moss
Sporophyte
Gametophyte
Liverworts
• Have no true roots
or shoots
• Non- vascular
• Require water to
reproduce
• Have no or very
little leaf structure
• Cannot live in
sporophyte form
Hornworts
• Free-floating
aquatic plant, or
land plant
• No vascular tissue
• No true leaves or
roots
• Can live in both
gametophyte and
sporophyte forms
Mosses
• Land plant
• Most have no vascular
tissue
• Majority to life spent in
gametophyte
• Need water to breed
• No leaves or roots
• Sporophytes are
capsules on stalks
Vascular Plants
• Vascular plants have two types of
vascular tissue
– Xylem and phloem
• Xylem
– Conducts most of the water and minerals
– Includes dead cells called tracheids
• Phloem
– Distributes sugars, amino acids, and
other organic products
– Consists of living cells
Vascular Plants
• Vascular plants have roots
– Are organs that anchor vascular plants
– Enable vascular plants to absorb water and
nutrients from the soil
– May have evolved from subterranean stems
• Vascular plants have leaves
– Leaves are organs that increase the surface
area of vascular plants, thereby capturing
more solar energy for photosynthesis
Vascular Plants
• Two types of vascular plants: seedless and
seeded
• Seedless vascular plants form two phyla
– Lycophyta, including club mosses, spike mosses,
and quillworts
– Pterophyta, including ferns, horsetails, and
whisk ferns and their relatives
• Modern species of lycophytes are relics
from a far more eminent past
– Are small herbaceous plants
• Ferns
– Are the most diverse seedless vascular plants
Seedless Vascular Plants
LYCOPHYTES (PHYLUM LYCOPHYTA)
PTEROPHYTES (PHYLUM PTEROPHYTA)
WHISK FERNS AND RELATIVES
HORSETAILS
FERNS
Isoetes
gunnii,
a quillwort
Selaginella apoda,
a spike moss
Diphasiastrum tristachyum, a club moss
Strobili
(clusters of
sporophylls)
Psilotum
nudum,
a whisk
fern
Equisetum
arvense,
field
horsetail
Vegetative stem
Strobilus on
fertile stem
Athyrium
filix-femina,
lady fern
Ferns
• Like vascular
plants but do not
have seeds
– Common in shady
areas, diverse in
the tropics
– Have flagellated
sperm that require
water to reach the
eggs
Alternation of Generations
• The seed plant life cycle contains both
haploid and diploid stages
– Diploid individuals are called sporophytes
– Haploid individuals are called
gametophytes
• Does not happen in algae
• May have evolved as an adaptation to
harsh environments
– Haploid cells divide into a cluster of cells
before meiosis
Alternation of Generations
HAPLOID
Meiosis
Spores
n
M
ito
si
s
Gametophytes
(male and female)
n
M
ito
sis
Gametes
(sperm and eggs)
n
Fertilization
Zygote
2n
M
ito
si
s
DIPLOID
Sporophyte
2n
Dominant Gametophyte
• Mosses have a dominant gametophyte stage
Sperm (n) (released from
their gametangium)
1
2
3
4
Gametangium
containing the egg (n)
(remains within
gametophyte)
Egg
Fertilization
Zygote
(2n)
Mitosis and
development
Sporophytes (growing from gametophytes)
HAPLOID
DIPLOID
Gametophyte
(n)
Sporangium
Stalk
Meiosis
Spores
(n)
5
Mitosis and
development
Gametophytes
(n)
Dominant Sporophyte
• Most plants have a dominant
sporophyte stage
1
2
3
4
Gametophyte (n)
(underside)
Sperm (n)
Egg (n)
Fertilization
Zygote
(2n)
Mitosis and
development
New sporophyte growing
out of gametophyte
Sporophyte (2n)
Meiosis
Sporangia
5
Spores
(n)
Mitosis and
development
HAPLOID
DIPLOID
Seeded Vascular Plants
• Gymnosperms-
conifers, cycads,
and ginkgo
• Angiosperms-
flowering plants