An Overview of Land Plant
Evolution
(Ch. 29, Plant Diversity I)
1) origin from ancestors similar to
charophytes
2) bryophytes
3) ferns
4) other spore-dispersed plants
1) origin from ancestors similar to charophytes…
The evolution
of land plants
involves
changes in
plant
development
related to
reproductive
biology.
Chara - a charophyte - the whole plant body is haploid except for the
zygote
zygote
egg and sperm production close up
The origin of the land-plants includes a delay in meoisis, so that there
are diploid vegetative cells in the life cycle.
cuticle, a critical invention
for land plants
1) origin from ancestors similar to charophytes…
1) origin from ancestors similar to charophytes…
Table 25.1, chapter 25, p. 515
Table 25.1, chapter 25, p. 515
An Overview of Land Plant
Evolution
1) origin from ancestors similar to
charophytes
2) bryophytes
3) ferns
4) other spore-dispersed plants
bryophytes:
• Ca. 15,000 species
• Gametophyte shoot with leaves
is common.
• Unbranched sporophyte, which
has stomates
Moss
Life Cycle
Spores produced in sporangium
operculum
D,E: Liverworts
peristome teeth
A-C: Mosses
F, G: Hornworts
Marchantia, a thallose liverwort
Bazzania, a leafy liverwort
archegonium of a liverwort
antheridium of a hornwort
sporophytes of two mosses
haircap moss
peat moss—Sphagnum
moss spores—products of meiosis
An Overview of Land Plant
Evolution
1) origin from ancestors similar to
charophytes
2) bryophytes
3) ferns
4) other spore-dispersed plants
Life cycle for the ferns
The ferns, with 12,000 species, are the most successful sporedispersed vascular plants.
Most ferns have a creeping stem and divided leaves…
xylem
phloem
Vascular tissue—for
moving fluids and
providing structural
support—is divided into
xylem and phloem.
Sporangia are in groups called sor
one sorus with sporangia hidden underneath
an indusium
Spores are produced
by meiosis in the
sporangium.
Spores germinate to produce haploid
gametophytes.
The gametophytes don’t
have shoots or vascular tissue.
Fertilization
Fertilization yields new diploid sporophytes.
An Overview of Land Plant
Evolution
1) origin from ancestors similar to
charophytes
2) bryophytes
3) ferns
4) other spore-dispersed plants
1) origin from ancestors similar to charophytes…
the horsetails,
Equisetum
a clubmoss, Lycopodium
a coal swamp, dominated by spore-dispersed plants
Table 25.1, chapter 25, p. 515
Fossil spore tetrads from the Cambrian are evidence of the
origin of the land-plant lineage and its life cycle:
Table 25.1, chapter 25, p. 487
Table 25.1, chapter 25, p. 487
1) origin from ancestors similar to charophytes…