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