29-30: Kingdom Plantae
What constitutes a plant?
What are the evolutionary trends in plants?
What are the reproductive trends in plants?
The Netherlands
What constitutes a plant?
Plants are:
Multicellular
Eukaryotes
Photosynthetic autotrophs
Algae may also have these characteristics.
Plants appear to have developed from algae.
Other features that plants and algae have in common:
Presence of chrolophyll b as an accessory pigment
Cellulose cell walls
Starch as storage product of surplus carbohydrates
Plants occur both on land and in water. Algae only in the presence
of water.
29.4 Where is
the line dividing
land plants from
algae?
Three possible
plant
kingdoms?
Embryophytes:
Plants with
embryos
Figure 29.7 Some highlights of plant evolution
1. Walled spores toughened by sporopollenin
2. Multicellular, dependent embryos
3. Apical meristems (root, shoot)
4. Presence of a waxy cuticle
[See book p. 602-603]
29.5. Walled spores produced in
sporangia.
Spores are haploid reproductive cells
that can grow into gametophytes (n)
by mitosis. Sporopollenin makes the
walls of spores very tough and
protects them against dehydration
Multicellular, dependent embryos
Develop from zygotes that are
retained within tissue from the
female parent
29.5. Apical meristem
Figure 35.18. Leaf anatomy (incl. waxy cuticle)
Figure 3.3 Vascular tissue – support against gravity and transport system
Phloem
in plants
Cambium
Xylem: Water conducting cells
Lignin: Hard material embedded in cellulose cell walls for structural support
Figure 29.5 Alternation of generations: a generalized scheme
A hypothetical mechanism for the origin of alternation of
generations in the ancestor of plants
Figure 29.7 Some highlights of plant evolution
Table 29.1
Ten Phyla
(Divisions) of
Extant Plants
(Embryophytes)
Figure 29.3 Charophyceans
The closest algal relatives of land plants
Chara (top), Coleochaete orbicularis (bottom)
29.4
Chara
Figure 29.7 Some highlights of plant evolution
29.9. Bryophytes
Liverworts
Hornworts
Mosses
Figure 29.8 The life cycle of
a moss (Polytrichum)
Figure 29.8 The life cycle of
a moss (Polytrichum)
gametophyte
Moss life cycle
sporophyte
archegonium
sporangium
spores
protonema
Marchantia, a liverwort
Gametangia:
Archegonium of Marchantia (left), Anteridium of a hornwort (right)
A moss sporangium with a “spore-shaker” tip
Bryophytes
Liverworts
Hornworts
Mosses
Sphagnum, or peat moss: Peat bog in Oneida County, Wisconsin (top), close-up of
Sphagnum (bottom left), Sphagnum "leaf" (bottom right)
A peat moss bog in Norway
Carbon reservoir  may help stabilize global atmospheric CO2
29.11. More than 2000-year old
bog mummy preserved in acid,
oxygen poor Sphagnum
wetlands
29.11. Peat, partially
decayed organic material,
harvested from peat moss
(Sphagnum) wetlands.
Decomposition is slow due
to cold temperatures, acid
conditions and little oxygen.
Figure 29.7 Some highlights of plant evolution
Xylem cells in angiosperms (see also Fig 35.10)
Lignin
Seedless Vascular plants
- Ferns
Figure 29.16 Lycophyta and Pterophyta. Artist’s conception of a
Carboniferous forest based on fossil evidence (some 350 million yrs B.P.)
29.15. Lycophytes: club "moss" (top left), many are epiphytes
Pterophytes: whisk fern (top right), horsetail (bottom left), fern (bottom right)
strobulus
Lycophyta
Pterophyta
Figure 29.13 The life cycle of a fern
Figure 29.13 The life cycle of a fern
Life cycle of a fern: mature fern
Life cycle of a fern: sorus
Life cycle of a fern: sporangium
Life cycle of a fern: mature sporangium
Life cycle of a fern: germinating
Life cycle of a fern: gametophyte
Life cycle of a fern: sporophytes
29.15. Lycophytes: club "moss" (top left)
Pterophytes: whisk fern (top right), horsetail (bottom left), fern (bottom right)
Lycophyta
Pterophyta
Figure 29.13 The life cycle of a fern
Heterospory: The sporophyte has two types of sporangia that produce two
types of spores, which develop into either female or male
unisexual gametophytes.
Spores:
• Megaspore, developing into a female gametophyte, which will
produce an egg
• Microspore, developing into a smaller male gametophyte, which
produces sperm
Which of the following is TRUE of
seedless vascular plants?
A. They produce many spores, which are really
the same as seeds.
B. Seedless vascular plants are all heterosporous.
C. Whole forests were dominated by large,
vascular seedless plants more than 300 million
years ago.
D. The few seedless vascular plants still living are
large and rare.
E. None of the above are true. Vascular plants
never form seeds.
Chapter 29 –Review (p. 616)
•
•
•
Concept 29.1. Land plants evolved from
green algae
Concept 29.2. Mosses and other nonvascular plants have life cycles
dominated by gametophytes
Concept 29.3. Ferns and other seedless
vascular plants were the first plants to
grow tall