Chapter 19 Plants Man: ©G. R. "Dick" Roberts/Natural Sciences Image Library Copyright © McGraw-Hill Education. All rights reserved. No reproduction or

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.

Plants Have Changed the World

Section 19.1 Figure 19.1

Members of kingdom Plantae are nearly everywhere.

Snow: ©Design Pics/Carson Ganci/Getty Images RF; Prairie: ©Tetra Images/Tetra Images/Corbis RF; Forest: ©Ted Mead/Getty Images RF

Plants harness the energy that sustains ecosystems. They also release O2, which consumers use for respiration.

Section 19.1

Highlights in the History of Plants

Figure 19.3

The presence or absence of vascular tissue, pollen and seeds, and flowers defines each plant group.

Section 19.1


Figure 19.3

Bryophytes have no vascular tissue, seeds, or flowers. Mosses are bryophytes.

Section 19.1


Figure 19.3

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

Vascular tissue consists of phloem and xylem. Phloem transports sugars. Xylem transports water.


Figures 19.3, 19.4Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

Section 19.1

Lignin is a complex polymer that strengthens cell walls in vascular tissue.


Figures 19.3, 19.4Stem cross section: © Dr. John D. Cunningham/Visuals Unlimited

Section 19.1


Figure 19.3

Modifications in vascular tissue led to the evolution of seedless vascular plants, like ferns.

Section 19.1


Figure 19.3

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


Cone scale

Seed

Gymnosperms are plants with vascular tissue and seeds, such as pine trees.

Pine cones: © Westend61/Alamy RF Figures 19.3, 19.4

Section 19.1


Figure 19.3

More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants.

Section 19.1


More recently, the origin of flowers and fruits introduced new reproductive adaptations. Angiosperms are flowering plants.

Seed containsembryo and its

food supply

Fertilized flowers develop into fruits that protect and

disperse seeds

Figures 19.3, 19.4Pea pods: ©Corbis RF

Section 19.1

The plant life cycle is called alternation of generations, in which a multicellular diploid stage alternates with a multicellular haploid stage.

All Plants Have Similar Life Cycles

Figure 19.5

Section 19.1

A zygote develops by mitotic cell division into a multicellular, diploid sporophyte.


Figure 19.5

Section 19.1

The sporophyte produces haploid spores by meiosis.


Figure 19.5

Section 19.1

Haploid spores divide by mitosis into a multicellular, haploid gametophyte.


Figure 19.5

Section 19.1

The haploidgametophyte produces gametes by mitotic cell division.


Figure 19.5

Section 19.1

These sex cells fuse at fertilization, forming a diploid zygote and starting the cycle anew.


Figure 19.5

Section 19.1

The sporophyte and gametophyte shown in this generalized plant life cycle are those of a seedless vascular plant.


Figure 19.5

Section 19.1

Substituting images in the alternation of generations produces diagrams of other plant life cycles.


Figure 19.21

Section 19.2

Bryophytes Are the Simplest Plants

Figure 19.3

Section 19.2


Bryophytes are seedless plants that lack vascular tissue. They also lack true leaves and roots.

Figure 19.7Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

Section 19.2


Materials move from cell to cell within the plant by diffusion and osmosis.

Figure 19.7Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The Mcgraw-Hill Companies

Section 19.2


Examples of bryophytes include:

LiverwortsHornwortsMosses

Figure 19.7Liverwort: ©Edward S. Ross; Hornwort: ©William E. Ferguson; Moss: ©Steven P. Lynch/The McGraw-Hill Companies

Section 19.2


The bryophyte life cycle is an alternation of generations.

Section 19.2


Figure 19.9Bryophytes: ©Ed Reschke

Bryophyte life cycle overview

Key

Haploid (n)

Diploid (2n) Protonemata(n)

“Bud”

“Bud”

Malegametophyte(n)

Femalegametophyte (n)

Gametophore

Rhizoid

Spores

Sporedispersal

Peristome

Sporangium

MEIOSIS SetaCapsule(sporangium)

Foot

Maturesporophytes

Capsule withperistome (SEM)

Femalegametophytes

2 m

m

Raindrop

Sperm

Antheridia

Egg

Archegonia

FERTILIZATION

(within archegonium)Zygote(2n)

Embryo

Archegonium

Youngsporophyte(2n)

Moss Life Cycle

Section 19.3

Seedless Vascular Plants

Figure 19.3



Examples of seedless vascular plants include:

Lycopods (not shown)Whisk fernsTrue fernsHorsetails

Whisk fern: ©W. Ormerod/Visuals Unlimited; Horsetail: ©Ed Reschke; Beech fern: ©Rod Planck/Science Source

Seedless vascular plants have xylem and phloem but not seeds. These plants typically have true roots, stems, and leaves.

Section 19.3

The seedless vascular plant life cycle is an alternation of generations.


Section 19.3


Figure 19.11Spores: ©Ed Reschke/Peter Arnold/Getty Images; Fern gametophyte: ©Les Hickok and Thomas Warne, C-Fern

Seedless vascular plant life cycle overview

Fern Life CycleKey

Haploid (n)

Diploid (2n)

MEIOSISSporedispersal

Sporangium

SporangiumMaturesporophyte(2n)

Sorus

Fiddlehead

Spore(n)

Younggametophyte

Maturegametophyte(n) Archegonium

Egg

Antheridium

Sperm

FERTILIZATION

Newsporophyte

Gametophyte

Zygote(2n)

Section 19.4

Gymnosperms Are “Naked Seed” Plants

Figure 19.3

Section 19.4

The sporophytes of most gymnosperms are woody trees or shrubs. Reproductive structures and leaf types are diverse.

Figure 19.12


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

Gymnosperms are divided into four groups:

Figure 19.12


Cycads Ginkgo 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

Gymnosperm life cycle is an alternation of generations.



Gymnosperms Are “Naked Seed” PlantsGymnosperm life cycle overview

Microsporangium (2n)

Microsporocytes(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS

Maturesporophyte(2n)

Haploid (n)Diploid (2n)

Key

MEIOSIS

Survivingmegaspore (n)

Pollengrain

Megasporocyte (2n)

Ovule

Integument

Ovulatecone

FERTILIZATION

Pollentube

Femalegametophyte

Spermnucleus (n)

Egg nucleus (n)

Archegonium

Seedling

Seeds

Seed coat(2n)

Foodreserves(n)

Embryo(2n)

Megasporangium(2n)

Pine Life Cycle

Section 19.5

Angiosperms Produce Seeds in Fruits

Figure 19.3

Section 19.5

Today, most plant species have reproductive structures called flowers, which develop into seed-toting fruits.

Figure 19.16


Red maple flower: ©Dwight Kuhn; cattails: ©Hans Reinhard/Okapia/Science Source; bee: ©McGraw-Hill Education; banana flower: ©Igor Prahin/Flickr Open/Getty Images RF

Section 19.5

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.

Figure 19.16



Section 19.5

Variation in flowers and fruits is the result of millions of years of evolution.

Figure 19.16



Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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

Carpel

Ovule

Sepal

Petal

Stigma

Style

Ovary

Stamen Anther

Filament



Scientists classify the diverse angiosperms into several taxa, notably the eudicots and monocots.

Section 19.5

The angiosperm life cycle is an alternation of generations.



Angiosperms Produce Seeds in FruitsAngiosperm life cycle overview

Fig. 30-10-4

MEIOSIS

Key

MicrosporangiumMicrosporocytes (2n)

Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)

Male gametophyte(in pollen grain)(n)

Mature flower onsporophyte plant(2n)

Haploid (n)Diploid (2n)

MEIOSIS

Ovule (2n)

Ovary

Megasporangium(2n)

Megaspore(n)

Female gametophyte(embryo sac)

Antipodal cells

Central cell

Synergids

Egg (n)

Pollentube

Pollentube

Stigma

Sperm(n)

Discharged sperm nuclei (n)

FERTILIZATION

Germinatingseed

Embryo (2n)Endosperm (3n)Seed coat (2n)

Seed

Nucleus ofdevelopingendosperm(3n)

Zygote (2n)Eggnucleus (n)

Style

Sperm

Angiosperm Life Cycle

49

Figure 19.20

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Chapter 19 Plants Man: ©G. R. "Dick" Roberts/Natural Sciences Image Library Copyright © McGraw-Hill Education. All rights reserved. No reproduction or