1. Chapter 19
Plants
Man: ©G. R. "Dick" Roberts/Natural Sciences Image Library
Copyright © McGraw-Hill Education.  All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.

2. Plants Have Changed the World
Members of kingdom Plantae are nearly everywhere.
Plants harness the energy that sustains ecosystems. They also release O2, which consumers use for respiration.
Section 19.1
Snow: ©Design Pics/Carson Ganci/Getty Images RF; Prairie: ©Tetra Images/Tetra Images/Corbis RF; Forest: ©Ted Mead/Getty Images RF
Figure 19.1

3. Highlights in the History of Plants
The presence or absence of vascular tissue, pollen and seeds, and flowers defines each plant group.
Section 19.1
Figure 19.3

4. Highlights in the History of Plants
Bryophytes have no vascular tissue, seeds, or flowers.
Mosses are bryophytes.
Section 19.1
Figure 19.3

5. Highlights in the History of Plants
The origin of vascular tissue, which transports water and nutrients in the plant, allowed plants to grow taller. Taller plants reach above their neighbors in the struggle for sunlight.
Section 19.1
Figure 19.3

6. Highlights in the History of Plants
Vascular tissue consists of phloem and xylem.
Phloem transports sugars. Xylem transports water.
Section 19.1
Figures 19.3, 19.4
Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

7. Highlights in the History of Plants
Lignin is a complex polymer that strengthens cell walls in vascular tissue.
Section 19.1
Figures 19.3, 19.4
Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

8. Highlights in the History of Plants
Modifications in vascular tissue led to the evolution of
seedless vascular plants, like ferns.
Section 19.1
Figure 19.3

9. Highlights in the History of Plants
The origin of seeds—dormant, protected plant embryos with a nutrient supply—was also adaptive. Seeds might travel far from the parent and only germinate when conditions are favorable.
Section 19.1
Figure 19.3

10. Highlights in the History of Plants
Gymnosperms are plants with vascular tissue and seeds,
such as pine trees.
Cone scale
Seed
Section 19.1
Figures 19.3, 19.4
Pine cones: © Westend61/Alamy RF

11. Highlights in the History of Plants
More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants.
Section 19.1
Figure 19.3

12. Fertilized flowers develop into fruits that protect and disperse seeds
Highlights in the History of Plants
More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants.
Seed contains
embryo and its
food supply
Fertilized flowers develop into fruits that protect and disperse seeds
Section 19.1
Figures 19.3, 19.4
Pea pods: ©Corbis RF

13. All Plants Have Similar Life Cycles
The plant life cycle is called alternation of generations,
in which a multicellular diploid stage alternates with a multicellular haploid stage.
Section 19.1
Figure 19.5

14. All Plants Have Similar Life Cycles
A zygote develops by mitotic cell division into a multicellular, diploid sporophyte.
Section 19.1
Figure 19.5

15. All Plants Have Similar Life Cycles
The sporophyte produces haploid spores by meiosis.
Section 19.1
Figure 19.5

16. All Plants Have Similar Life Cycles
Haploid spores divide by mitosis into a multicellular, haploid gametophyte.
Section 19.1
Figure 19.5

17. All Plants Have Similar Life Cycles
The haploid
gametophyte produces gametes by mitotic cell division.
Section 19.1
Figure 19.5

18. All Plants Have Similar Life Cycles
These sex cells fuse at fertilization, forming a diploid zygote and starting the cycle anew.
Section 19.1
Figure 19.5

19. All Plants Have Similar Life Cycles
The sporophyte and gametophyte shown in this generalized plant life cycle are those of a seedless vascular plant.
Section 19.1
Figure 19.5

20. All Plants Have Similar Life Cycles
Substituting images in the alternation of generations produces diagrams of other plant life cycles.
Section 19.1
Figure 19.21

21. Bryophytes Are the Simplest Plants
Section 19.2
Figure 19.3

22. Bryophytes Are the Simplest Plants
Bryophytes are seedless plants that lack vascular tissue. They also lack true leaves and roots.
Section 19.2
Figure 19.7
Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

23. Bryophytes Are the Simplest Plants
Materials move from cell to cell within the plant by diffusion and osmosis.
Section 19.2
Figure 19.7
Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

24. Bryophytes Are the Simplest Plants
Examples of bryophytes include:
Liverworts
Hornworts
Mosses
Section 19.2
Figure 19.7
Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The McGraw-Hill Companies

25. Bryophytes Are the Simplest Plants
The bryophyte life cycle is an alternation of generations.
Section 19.2

26. Bryophytes Are the Simplest Plants
Bryophyte life cycle overview
Section 19.2
Figure 19.9
Bryophytes: ©Ed Reschke

27. Moss Life Cycle Figure 29.8 The life cycle of a moss Raindrop Sperm
“Bud”
Antheridia
Male
gametophyte
(n)
Key
Haploid (n)
Protonemata
(n)
Diploid (2n)
“Bud”
Egg
Spores
Gametophore
Archegonia
Spore
dispersal
Female
gametophyte (n)
Rhizoid
Peristome
Sporangium
FERTILIZATION
Figure 29.8 The life cycle of a moss
MEIOSIS
(within archegonium)
Seta
Zygote
(2n)
Capsule
(sporangium)
Mature
sporophytes
Foot
Embryo
Archegonium
Young
sporophyte
(2n)
2 mm
Capsule with
peristome (SEM)
Female
gametophytes

28. Seedless Vascular Plants
Section 19.3
Figure 19.3

29. Seedless Vascular Plants
Examples of seedless vascular plants include:
Lycopods (not shown)
Whisk ferns
True ferns
Horsetails
Seedless vascular plants have xylem and phloem but not seeds. These plants typically have true roots, stems, and leaves.
Section 19.3
Figure 19.10
Whisk fern: ©W. Ormerod/Visuals Unlimited; Horsetail: ©Ed Reschke; Beech fern: ©Rod Planck/Science Source

30. Seedless Vascular Plants
The seedless vascular plant life cycle is an alternation of generations.
Section 19.3

31. Seedless Vascular Plants
Seedless vascular plant life cycle overview
Section 19.3
Figure 19.11
Spores: ©Ed Reschke/Peter Arnold/Getty Images; Fern gametophyte: ©Les Hickok and Thomas Warne, C-Fern

32. Fern Life Cycle Key Haploid (n) Diploid (2n) Spore (n) Antheridium
Young
gametophyte
Spore
dispersal
MEIOSIS
Sporangium
Mature
gametophyte
(n)
Sperm
Archegonium
Egg
Mature
sporophyte
(2n)
Sporangium
New
sporophyte
Zygote
(2n)
FERTILIZATION
Sorus
Figure The life cycle of a fern
Gametophyte
Fiddlehead

33. Gymnosperms Are “Naked Seed” Plants
Section 19.4
Figure 19.3

34. Gymnosperms Are “Naked Seed” Plants
The sporophytes of most gymnosperms are woody trees or shrubs. Reproductive structures and leaf types are diverse.
Cycad tree: ©Alena Brozova/Alamy; cycad seed: ©Pat Pendarvis; ginko tree: ©Light of Peace/Flickr/Getty Images RF; ginko seed: ©G. R. "Dick" Roberts/Natural Sciences Image Library; conifer tree: ©Jack Dykinga/Nature Picture Library; pine cone: ©Ed Reschke/Peter Arnold/Getty Images; ephedra: ©Gerald & Buff Corsi/Visuals Unlimited; ephedra reproductive structures: ©Edward S. Ross
Section 19.4
Figure 19.12

35. Gymnosperms Are “Naked Seed” Plants
Gymnosperms are divided into four groups:
Ginkgo
Cycads
Conifers
Gnetophytes
Cycad tree: ©Alena Brozova/Alamy; cycad seed: ©Pat Pendarvis; ginko tree: ©Light of Peace/Flickr/Getty Images RF; ginko seed: ©G. R. "Dick" Roberts/Natural Sciences Image Library; conifer tree: ©Jack Dykinga/Nature Picture Library; pine cone: ©Ed Reschke/Peter Arnold/Getty Images; ephedra: ©Gerald & Buff Corsi/Visuals Unlimited; ephedra reproductive structures: ©Edward S. Ross
Section 19.4
Figure 19.12

36. Gymnosperms Are “Naked Seed” Plants
Gymnosperm life cycle is an alternation of generations.
Section 19.4

37. Gymnosperms Are “Naked Seed” Plants
Gymnosperm life cycle overview
Section 19.4
Figure 19.13

38. Pine Life Cycle Key Haploid (n) Ovule Diploid (2n) Ovulate cone
Megasporocyte (2n)
Integument
Pollen cone
Microsporocytes (2n)
Mature sporophyte (2n)
Megasporangium (2n)
Pollen grain
Pollen grains (n)
MEIOSIS
MEIOSIS
Microsporangia
Microsporangium (2n)
Surviving megaspore (n)
Seedling
Archegonium
Figure 30.6 The life cycle of a pine
Seeds
Female gametophyte
Food reserves (n)
Sperm nucleus (n)
Seed coat (2n)
Pollen tube
Embryo (2n)
FERTILIZATION
Egg nucleus (n)

39. Angiosperms Produce Seeds in Fruits
Section 19.5
Figure 19.3

40. Angiosperms Produce Seeds in Fruits
Today, most plant species have reproductive structures called flowers, which develop into seed-toting fruits.
Section 19.5
Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF
Figure 19.16

41. Angiosperms Produce Seeds in Fruits
Flowers produce pollen and eggs; wind or animals usually carry pollen from plant to plant. Fruits protect the seeds and disperse them to new habitats.
Section 19.5
Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF
Figure 19.16

42. Angiosperms Produce Seeds in Fruits
Variation in flowers and fruits is the result of millions of years of evolution.
Section 19.5
Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF
Figure 19.16

43. Flowers
The flower is an angiosperm structure specialized for sexual reproduction
Many species are pollinated by insects or animals, while some species are wind-pollinated
A flower is a specialized shoot with up to four types of modified leaves:
Sepals, which enclose the flower
Petals, which are brightly colored and attract pollinators
Stamens, which produce pollen on their terminal anthers
Carpels, which produce ovules

44. Stigma Carpel Stamen Anther Style Filament Ovary Petal Sepal Ovule
Figure 30.7 The structure of an idealized flower
Petal
Sepal
Ovule

45. Angiosperms Produce Seeds in Fruits
Scientists classify the diverse angiosperms into several taxa, notably the eudicots and monocots.
Section 19.5
Figure 19.14

46. Angiosperms Produce Seeds in Fruits
The angiosperm life cycle is an alternation of generations.
Section 19.5

47. Angiosperms Produce Seeds in Fruits
Angiosperm life cycle overview
Section 19.5
Figure 19.15

48. Angiosperm Life Cycle Key Haploid (n) Diploid (2n) Microsporangium
Fig
Angiosperm Life Cycle
Key
Haploid (n)
Diploid (2n)
Microsporangium
Anther
Mature flower on sporophyte plant (2n)
Microsporocytes (2n)
MEIOSIS
Generative cell
Microspore (n)
Ovule (2n)
Tube cell
Male gametophyte (in pollen grain) (n)
Ovary
Pollen grains
MEIOSIS
Germinating seed
Stigma
Megasporangium (2n)
Pollen tube
Embryo (2n) Endosperm (3n) Seed coat (2n)
Sperm
Seed
Megaspore (n)
Style
Antipodal cells Central cell Synergids Egg (n)
Figure The life cycle of an angiosperm
Female gametophyte (embryo sac)
Pollen tube
Sperm (n)
Nucleus of developing endosperm (3n)
FERTILIZATION
Zygote (2n)
Egg nucleus (n)
Discharged sperm nuclei (n)

49. Figure 19.20