1. Plant Kingdom

2. Cell Wall
protects and provides skeletal support that helps keep the plant upright and
is primarily composed
of cellulose.
Ribosomes
Plasma membrane
Microfilament
Microtubule
CYTOSKELETON
Cell wall of adjacent cell
Plasmodesma
Cell wall
Chloroplast
Central vacuole

3. Chloroplast An oval, green structure found in plants and some bacteria
Contains chlorophyll that captures sun’s energy and produces sugars
Comparable to solar power facility

4. Plants have adaptations for life on land
More than 500 million years ago, the algal ancestors of plants may have carpeted moist fringes of lakes and coastal salt marshes.
Some species accumulated adaptations that enabled them to live permanently above the water line.

5. Plants have adaptations for life on land
Plants and green algae called charophytes
are thought to have evolved from a common ancestor,
have complex multicellular bodies,
are photosynthetic eukaryotes.

6. Plants have adaptations for life on land
Life on land benefits
unlimited sunlight,
abundant CO2, and
initially, few pathogens or herbivores.

7. Plants have adaptations for life on land
Life on land had disadvantages, too. On land, plants must
maintain moisture inside their cells, to keep from drying out,
support their body without water,
reproduce and disperse offspring without water,
anchor their bodies in soil, and
obtain resources from soil and air.

8. Plants have adaptations for life on land
Unlike land plants, algae
generally have no rigid tissues,
are supported by surrounding water,
obtain CO2 and minerals directly from the water
receive light over most of their body,
use flagellated sperm that swim to fertilize an egg
disperse offspring by water.

9. Plants have adaptations for life on land
Organisms that were able to overcome the obstacles on land thrived
Land plants maintain moisture in their cells using
a waxy cuticle and
cells that regulate the opening and closing of stomata.
Land plants obtain
water and minerals from roots in the soil,
CO2 from the air, and
sunlight through leaves.

10. Plants have adaptations for life on land
In many land plants, water and minerals move up from roots to stems and leaves using vascular tissue.
Xylem
consists of dead cells and
conveys water and minerals.
Phloem
consists of living cells and
conveys sugars.

11. Plants have adaptations for life on land
The cell walls of some plant tissues, including xylem, are thickened and reinforced by a chemical called lignin.
The absence of lignified cell walls in mosses and other plants that lack vascular tissue limits their height.

12. Plants have adaptations for life on land
In all plants,
gametes and embryos must be kept moist,
fertilized eggs (zygotes) develop into an embryo while attached to and nourished by the parent plant, and
the life cycle involves an alternation of a haploid generation, which produces eggs and sperm, and a diploid generation, which produces spores within protective structures called sporangia.

13. Lycophytes (club mosses, spike mosses, quillworts)
Figure 17.2a-0
Liverworts
Mosses
Hornworts
Lycophytes (club mosses, spike mosses, quillworts)
Monilophytes (ferns,
horsetails, whisk ferns)
Gymnosperms
Angiosperms
Land plants
Vascular plants
Nonvascular plants (bryophytes)
Seedless
vascular plants
Seed plants
Millions of years ago (mya)
500
Ancestral green alga
Origin of land plants (about 470 mya)
Origin of vascular plants (about 425 mya)
Origin of seed plants (about 360 mya) 1
450
400
350
300 2 3
Figure 17.2a-0 Some highlights of plant evolution

14. Recall Classification
Life
Archaea Bacteria Eukarya
Archaea Bacteria Protista Plantae Fungi Animalia
Non vascular plants Seedless Vascular Gymnosperms Angiosperms
(Bryophytes) (Vascular Seed Plants)

15. Plant diversity reflects the evolutionary history of the plant kingdom
Early diversification of plants gave rise to seedless, nonvascular plants called bryophytes, including
mosses,
liverworts, and
hornworts.

16. Plant diversity reflects the evolutionary history of the plant kingdom
Bryophytes resemble other plants in many ways, but they lack
true roots,
leaves, and
lignified cell walls.

17. Alternation of Generations
Plants have an alternation of generations in which the haploid and diploid stages are distinct, multicellular bodies.
The haploid generation of a plant produces gametes and is called the gametophyte.
The diploid generation produces spores and is called the sporophyte.

18. Alternation of Generations
In a plant’s life cycle, these two generations alternate in producing each other.
In mosses, as in all nonvascular plants, the gametophyte is the larger, more obvious stage of the life cycle.
Ferns, like most plants, have a life cycle dominated by the sporophyte.
Sporophyte
Gametophyte

20. A Moss Life Cycle Key Haploid (n) Diploid (2n) Male gametangium Sperm
Female gametangium
Egg
Gametophyte plants (n)
Figure Moss life cycle (step 1)

21. A Moss Life Cycle Key Haploid (n) Diploid (2n) Male gametangium Sperm
Female gametangium
Egg
Gametophyte plants (n)
Fertilization
Figure Moss life cycle (step 2)
Zygote

22. A Moss Life Cycle Key Haploid (n) Diploid (2n) Male gametangium Sperm
Female gametangium
Egg
Gametophyte plants (n)
Sporangium
Sporophyte
Fertilization
Figure Moss life cycle (step 3)
Zygote
Gametophyte

23. A Moss Life Cycle Key Haploid (n) Diploid (2n) Male gametangium Sperm
Female gametangium
Egg
Gametophyte plants (n)
Spores (n)
Sporangium
Sporophyte
Fertilization
Figure Moss life cycle (step 4)
Zygote
Meiosis
Gametophyte

24. A Moss Life Cycle Key Haploid (n) Diploid (2n) Male gametangium Sperm
Female gametangium
Egg
Gametophyte plants (n)
Spores (n)
Sporangium
Sporophyte
Fertilization
Figure Moss life cycle (step 5)
Zygote
Meiosis
Gametophyte