chapter 22: the diversity of plants · 596 the diversity of plants the diversity of plants what...

Chapter 22 OrganizerChapter 22 Organizer

Activities/FeaturesObjectivesSection

MATERIALS LIST

BioLabp. 618 conifer twigs, conifer branches,conifer cones

MiniLabsp. 606 microscope, microscope slide,coverslip, forceps, water, glycerin, livefern frondp. 609 lima beans, grass seeds, rice,peas, rye seeds, forceps, iodine stain,dropper, pencil, paper

Alternative Labp. 612 microscope, prepared slide ofconifer leaf cross section

Quick Demosp. 599 flowerpots (2), sand, peat moss,waterp. 602 capillary tube, petri dish, water,food coloringp. 610 assorted conifer cones

Need Materials? Contact Carolina Biological Supply Company at 1-800-334-5551or at http://www.carolina.com

Teacher Classroom Resources

Assessment Resources Additional Resources

Products Available FromGlencoeTo order the following products,call Glencoe at 1-800-334-7344:CD-ROMNGS PictureShow: What ItMeans to Be GreenCurriculum KitGeoKit: PlantsTransparency SetNGS PicturePack: What It Meansto Be GreenVideodiscSTV: Plants

Index to NationalGeographic MagazineThe following articles may beused for research relating to thischapter:“The Gift of Gardening,” byWilliam S. Ellis, May 1992.

Teacher’s Corner

596B596A

The Diversity of PlantsThe Diversity of Plants

TransparenciesReproducible MastersSection

NonvascularPlants

Non-SeedVascular Plants

Seed Plants

Section 22.1

Section 22.2

Section 22.3

Teacher Classroom Resources

Section Focus Transparency 52

Section Focus Transparency 53

Section Focus Transparency 54Basic Concepts Transparency 34Basic Concepts Transparency 35

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS

P

ELL

LS

L1

P

LS

P

ELL

LS

L1

P

LS

P

ELL

LS

L1

P

LS

Assessment Resources Additional ResourcesSpanish ResourcesEnglish/Spanish AudiocassettesCooperative Learning in the Science ClassroomLesson Plans/Block Scheduling

COOP LEARN

LS

P

ELL

LS

L1

P

LS

P

ELL

LS

L1

P

LS

Chapter Assessment, pp. 127-132MindJogger VideoquizzesPerformance Assessment in the Biology ClassroomAlternate Assessment in the Science ClassroomComputer Test BankBDOL Interactive CD-ROM, Chapter 22 quiz

Refer to pages 4T-5T of the Teacher Guide for an explanation of the National Science Education Standards correlations.

Nonvascular PlantsNational Science EducationStandards UCP.1, UCP.5;A.1, A.2; C.1, C.5; G.1-3 (1 session)

Non-Seed VascularPlantsNational Science EducationStandards UCP.1-5; A.1, A.2;C.1, C.3, C.5, C.6; G.3 (1 session)

Seed PlantsNational Science EducationStandards UCP.1-5; A.1, A.2;C.1, C.3, C.5, C.6; F.3-6;G.1-3 (2 sessions, 11/2 blocks)

1. Identify the structures of nonvascularplants.

2. Compare and contrast characteristicsof the different groups of nonvascularplants.

3. Explain the importance of vascular tissue to life on land.

4. Identify the characteristics of the non-seed vascular plant divisions.

5. Identify the characteristics of seedplants.

6. Analyze the advantages of seed andfruit production.

Problem-Solving Lab 22-1, p. 598

Problem-Solving Lab 22-2, p. 604MiniLab 22-1: Identifying Fern Sporangia, p. 606

MiniLab 22-2: Comparing Seed Types, p. 609Inside Story: Pine Needles, p. 613Careers in Biology: Lumberjack, p. 616Design Your Own BioLab: How can youmake a key for identifying conifers? p. 618Biology & Society: Forestry: Keeping aBalance, p. 620

Section 22.2

Section 22.1

Section 22.3

Reinforcement and Study Guide, p. 97Content Mastery, pp. 109-110, 112

Reinforcement and Study Guide, pp. 98-99BioLab and MiniLab Worksheets, p. 101Laboratory Manual, pp. 153-156Content Mastery, pp. 109-110, 112

Reinforcement and Study Guide, p. 100Concept Mapping, p. 22Critical Thinking/Problem Solving, p. 22BioLab and MiniLab Worksheets, pp. 102-104Laboratory Manual, pp. 157-160Content Mastery, pp. 109, 111-112 L1

P

LS

L2

P

LS

L2

P

LS

L3

P

LS

P

ELL

LS

L3

P

LS

L2

P

LS

L1

P

LS

L2

P

LS

L2

P

LS

L2

P

LS

L1

P

LS

L2

P

LS

Key to Teaching StrategiesKey to Teaching Strategies

Level 1 activities should be appropriatefor students with learning difficulties.Level 2 activities should be within theability range of all students.Level 3 activities are designed for above-average students.ELL activities should be within the abilityrange of English Language Learners.

Cooperative Learning activitiesare designed for small group work.These strategies represent student prod-ucts that can be placed into a best-workportfolio.These strategies are useful in a blockscheduling format.

L1

P

LS

L2

P

LS

L3

P

LS

P

ELL

LS

P

COOP LEARN

LS

PP

LS

P

LS

The following multimedia resources are available from Glencoe.

Biology: The Dynamics of LifeCD-ROM

Animation: Life Cycle of a MossExploration: The Six KingdomsBioQuest: Biodiversity ParkVideo: Fern DevelopmentExploration: Classifying PinesVideo: Giant RedwoodsExploration: AngiospermVideo: Blooming Flowers

The Infinite VoyageLife in the Balance

P

ELL

LS

http://www.carolina.com

Section

What Is a Nonvascular Plant?

Nonvascular plants are not as com-mon or as widespread in their distri-bution as vascular plants because lifefunctions, including photosynthesisand reproduction, require a closeassociation with water. Because asteady supply of water is not availableeverywhere, nonvascular plants arelimited to moist habitats by streamsand rivers or in temperate and tropi-cal rain forests. Recall that a lack ofvascular tissue also limits the size of aplant. In drier soils, nonvascularplants cannot compete with neigh-boring vascular plants, which can eas-ily overgrow them and cut them off

from sunlight and atmospheric gases.But even with these limitations, non-vascular plants are successful in habi-tats with adequate water.

Alternation of generations As in all plants, the life cycle of

nonvascular plants includes an alter-nation of generations between adiploid sporophyte and a haploidgametophyte. However, nonvascularplants are the only plant divisions inwhich the gametophyte generation isdominant. The gametophytes aredominant and the sporophytes arephysically attached to the gameto-phytes, as shown in Figure 22.1, anddependent on them for most of theirnutrition.

As you hike in a shady for-est, you are sure to comeacross patches of soft,

feathery mosses covering soil, rocks,rotting wood, or tree bark with avelvety layer of green. On closerexamination, you might also noticeshiny liverworts or odd-shapedhornworts along the stony bank of a stream. Mosses, liverworts,and hornworts are nonvascu-lar plants. These smallplants usually live in moist,cool environments.

SECTION PREVIEW

ObjectivesIdentify the structuresof nonvascular plants.Compare and contrastcharacteristics of the different groups of non-vascular plants.

Vocabularyantheridiumarchegonium

22.1 Nonvascular Plants

Moss-covered forest floor and liverwort (inset)

Figure 22.1 Brown stalks andspore capsules of thesporophyte genera-tion can be seengrowing from thegreen, leafy gameto-phyte of this moss.

597

Section 22.1

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 22,Section 22.1

SECTION FOCUS

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Transparency What’s Green andEssential for Life?52

Why do you think that plants such as these are essentialfor most life on Earth?

In what major way does the top pair of plants differfrom the bottom pair?

11

22

PrepareKey ConceptsCharacteristics of three divisionsof nonvascular plants are exam-ined with emphasis on their lackof vascular tissue and the limita-tions this places on mosses, liver-worts, and hornworts. A briefdiscussion of alternation of gen-erations among nonvascularplants is included.

Planning■ Purchase fruits and seeds for

the Getting Started Demo.■ Collect pictures of nonvascular

plants for the Display.■ Purchase sand and peat moss

for the Quick Demo.

1 FocusBellringer Before presenting the lesson, display Section Focus Trans-parency 52 on the overhead pro-jector and have students answerthe accompanying questions.

P

ELL

LS

L1

P

LSAssessment PlannerAssessment Planner

Portfolio AssessmentAssessment, TWE, p. 600MiniLab, TWE, p. 609

Performance AssessmentMiniLab, SE, pp. 606, 609Alternative Lab, TWE, p. 612BioLab, SE, p. 618-619BioLab, TWE, p. 619

Knowledge AssessmentProblem-Solving Lab, TWE, p. 598

Section Assessment, SE, pp. 600, 607, 617MiniLab, TWE, p. 606Assessment, TWE, pp. 607, 610, 615Chapter Assessment, SE, pp. 621-623

Skill AssessmentAssessment, TWE, pp. 599, 602, 617Problem-Solving Lab, p. 604Alternative Lab, TWE, p. 613

596 THE DIVERSITY OF PLANTS

The Diversity of Plants

What You’ll Learn■ You will identify the charac-

teristics of the major plantgroups.

■ You will compare the distin-guishing features of vascularand nonvascular plants.

■ You will analyze the advan-tages of seed production.

Why It’s ImportantWe classify plants according totheir characteristics. Knowingabout the major characteristicsof plants will help you appreci-ate the beauty and diversity ofthe plants around you.

Comparing Seeds and FruitsExamine a number of differentseeds and fruits. How do youthink these seeds and fruitsmight be transported awayfrom their parent plant?

To find outmore about

the diversity of plants, visit theGlencoe Science Web Site. www.glencoe.com/sec/science

22

GETTING STARTEDGETTING STARTED

ChapterChapter

Members of the plantkingdom exhibit a widevariety of characteristics.Some plants producelarge, colorful fruits.Others, including mosses,produce tiny spores.

596

Theme DevelopmentThe theme unity within diver-sity is carried out within thischapter as students learn aboutfeatures shared by nonvascularplants and vascular plants such asthe plant life cycle, whichincludes alternation of genera-tions. Diversity is illustratedthrough the unique adaptationsfound in members of the differ-ent divisions. Evolution is appar-ent through the discussions of themany adaptations plants exhibitthat aid in their survival.

Chapter 22Chapter 22

MultipleLearningStyles

Look for the following logos for strategies that emphasize different learning modalities.Kinesthetic Enrichment, p. 603;Meeting Individual Needs, p. 604;

Project, p. 605Visual-Spatial Portfolio, pp. 598,603, 614; Meeting Individual

Needs, p. 602; Extension, pp. 607, 617;Quick Demo, p. 610; ChalkboardActivity, p. 612

Interpersonal Activity, p. 600

Intrapersonal Enrichment, p. 611;Linguistic Biology Journal, pp.599, 603; Cultural Diversity, p.

609; Meeting Individual Needs, p. 611Logical-Mathematical Chalk-board Activity, p. 605; Biology

Journal, p. 610Naturalist Meeting IndividualNeeds, p. 598; Discussion, p. 607

GETTING STARTED DEMOGETTING STARTED DEMO

Visual-Spatial Show students pictures or live

samples of a variety of vascu-lar and nonvascular plants.Ask students to compare andcontrast the plants.

P

LS

L1

P

LS

If time does not permit teach-ing the entire chapter, use theBioDigest at the end of theunit as an overview.

Resource ManagerResource Manager

Section Focus Transparency 52and Master

P

ELL

LS

L1

P

LS

http://www.glencoe.com/sec/science

Mosses usually grow in densecarpets of hundreds of plants.Some have upright stems; oth-ers have creeping stems thathang from steep banks or treebranches. Some mosses formextensive mats that retard ero-sion on exposed rocky slopes.

Mosses grow in a wide vari-ety of habitats. They grow evenin the arctic in places wherethere is sufficient moisture.

One of the most well-knownmosses is Sphagnum moss, alsoknown to gardeners as peatmoss. This plant thrives inacidic bogs in northern regionsof the world. It has been harvestedfor use as fuel and is a commonlyused soil additive. Dried peat mossabsorbs large amounts of water, soflorists and gardeners use it toincrease the water-holding ability ofsoil. See Figure 22.2 to examine thecharacteristics of Bryum andSphagnum mosses.

Adaptations inHepatophyta

Another division of nonvascularplants is the liverworts, or hepato-phytes. Like mosses, liverworts aresmall plants that usually grow inclumps or masses in moist habitats.The name of the division is derivedfrom the word hepatic, which refers tothe liver. The flattened body of a liv-erwort gametophyte is thought toresemble the shape of the lobes of ananimal’s liver. Liverworts occur inmany environments, from the Arcticto the Antarctic. They include twogroups: the thallose liverworts andthe leafy liverworts, Figure 22.3.The body of a thallose liverwort is athallus. It is a broad, ribbonlike bodythat resembles a fleshy, lobed leaf.

Leafy liverworts are creeping plantswith three rows of flat, thin leavesattached to a stem. Like mosses, liv-erworts have rhizoids; however, therhizoids of liverworts are each com-posed of only one elongated cell.Most liverworts have an oily or shinysurface that helps reduce evaporationof water from the plant’s tissues.

Adaptations inAnthocerophyta

Anthocerophytes are the smallestdivision of nonvascular plants, cur-rently consisting of only about 100species. Also known as hornworts,these nonvascular plants are similar

22.1 NONVASCULAR PLANTS 599

OriginWORDWORD

antheridiumFrom the Greekword anthera,meaning “flowery.”Sperm are producedin the antheridium.

archegonium From the Greekword archegonos,meaning “origina-tor.” Eggs are produced in thearchegonium.

Figure 22.3 Liverworts may havea flattened thallus (a)or flattened leaves inthree ranks borne ona stem (b).

a

b

599

Skill Ask students to con-struct a table comparing and con-trasting the three divisions ofnonvascular plants. L2

P

LS

AssessmentAssessmentGametophytes produce two kindsof sexual reproductive structures.The antheridium (an thuh RIHD eeum) is the male reproductive struc-ture in which sperm are produced.The archegonium (ar kih GOH neeum) is the female reproductive struc-ture in which eggs are produced.Think of ways you can identify thephases of a nonvascular plant’s lifecycle in the Problem-Solving Labshown here.

Adaptations inBryophyta

There are several divisions of non-vascular plants. The first divisionyou’ll study are the mosses, orbryophytes. Bryophytes are the mostfamiliar of the nonvascular plant divi-sions. Mosses are small plants withleafy stems. The leaves of mosses areusually one cell thick. Mosses haverhizoids, colorless multicellularstructures, which help anchor thestem to the soil. Although mosses donot contain true vascular tissue, somespecies do have a few, long water-conducting cells in their stems.


Is it a sporophyte or a gametophyte? You have just dis-covered a new plant species and have classified it as a non-vascular plant. You have two almost identical specimens, andmicroscopic examination reveals the internal structures ofplants 1 and 2 below.

AnalysisFormulate a hypothesis as to the nature of plants 1 and 2.

Thinking Critically1. Compare part a to b. What is part a? How do you know?2. What is part b? How do you know?3. Knowing that this is a nonvascular plant, are plants 1 and

2 sporophytes or gametophytes? How do you know?4. Are parts a and b formed by mitosis or meiosis?

Are a and b haploid or diploid? Explain.5. Are plants 1 and 2 haploid or diploid? Explain.

Problem-Solving Lab 22-1Problem-Solving Lab 22-1 Observing andInferring

Figure 22.2Mosses have a central stem surroundedby small, thin leaves. They also have rhi-zoids, one-cell-thick rootlike structures,which absorb water and nutrients.

Peat moss, Sphagnum, is well-known because of its usefulnessto humans as fuel and in thehorticultural industry.

BB

Bryum is a type ofmoss frequentlyfound in moistforest habitats.

AA

Plant 2

b

x 1

x 50x 1

Plant 1a

x 1x 50 x 400

598

2 Teach

PurposeStudents will determine fromvarious clues that they areobserving plant gametophytes.

Process Skillsobserve and infer, think critically,analyze information, interpretscientific illustrations

BackgroundIt is not unusual to find male andfemale bryophyte gametophytes.The plant being used in this labis a liverwort.

Teaching Strategies■ Advise students to pay closeattention to the scale of magnifi-cation included on the diagrams.■ Students will have to havealready studied alternation ofgenerations and be familiar withthe contributions of the gameto-phyte generation in order tounderstand this lab.

Thinking Critically

1. Sperm cell; there are numer-ous cells with flagella.

2. Egg cell; it is a single cellmuch larger than part a.

3. Gametophytes; the gameto-phyte generation formsgametes.

4. Mitosis; haploid—gameto-phytes form gametes bymitosis.

5. Haploid; all parts of thegametophyte are haploid.

Knowledge Ask studentsto copy the diagrams and addlabels to the antheridium andarchegonium. Have students dia-gram the rest of this plant’s lifecycle. Use the Performance TaskAssessment List for ScientificDrawing in PASC, p. 55. L2

P

LS

AssessmentAssessment

P

LS

Problem-Solving Lab 22-1Problem-Solving Lab 22-1

MEETING INDIVIDUAL NEEDS MEETING INDIVIDUAL NEEDS

Learning DisabledNaturalist Have students list as many characteristics as possible that

distinguish the nonvascular plant divisionsfrom other plant groups. Organizing thesecharacteristics into lists will help studentswith learning disabilities to distinguishthese plant divisions.

P

LS

L1

P

LS

PortfolioPortfolio

Alternation of GenerationsVisual-Spatial Have students pre-pare a simple flowchart diagram

that depicts alternation of generations.The diagram must include these terms:gametophyte generation, sporophytegeneration, spore, gamete, diploid, andhaploid. Have students place the flow-chart in their portfolio.

P

LS

PP

LS

L2

P

LS

Quick DemoQuick Demo

Show students the water ab-sorption capabilities of peatmoss by pouring water into two flowerpots: one containingsand and the other containing a mix of sand and peat moss.P

LS

BIOLOGY JOURNAL BIOLOGY JOURNAL

Development or Conservation?Linguistic Tell students a hypotheticalstory involving the construction of an

affordable housing development in a partic-ularly attractive wooded area. Tell studentsthis area is known for the many varieties of

nonvascular plants found growing there.They are to write letters to the local govern-ment agency either supporting the develop-ment or calling for conservation of the area.Tell students they must include reasons fortheir views in this letter.

P

LS

L3

P

LS

VIDEODISCThe Secret of LifeA Moss

CD-ROMBiology: The Dynamicsof Life

Animation; Life Cycle of a MossDisc 3

!7;E8B"

DisplayMake a bulletin board display ofnonvascular plants.

3 AssessCheck for UnderstandingAsk students to explain the rela-tionships for the following wordpairs.

a. sperm—antheridiumb. egg—archegonium

P

ELL

LS

L1

P

LS

to liverworts in several respects. Likesome liverworts, hornworts have athallose body. As you can see inFigure 22.4, the sporophyte of ahornwort resembles the horn of ananimal, which is why members of thisdivision are commonly called "horn-worts." Another feature unique tohornworts is the presence of a singlelarge chloroplast in each cell. Thisfeature suggests that hornworts maybe closely related to algae, which alsohave only one large chloroplast ineach cell.

Origins of Nonvascular Plants

Fossil and genetic evidence sug-gests that liverworts were the firstland plants. Fossils that have beenpositively identified as nonvascularplants first appear in rocks from theearly Paleozoic period, about 430million years ago. However, paleo-botanists think that nonvascularplants were present much earlier thancurrent fossil evidence suggests. Bothnonvascular and vascular plants prob-ably share a common ancestor thathad alternating sporophyte andgametophyte generations, cellulosein their cell walls, and chlorophyll forphotosynthesis.


Section AssessmentSection Assessment

Understanding Main Ideas1. How can you tell a leafy liverwort from a

thallose liverwort?2. In what way is the sporophyte generation

of a moss dependent on the gametophyte generation?

3. What are some characteristics shared by all nonvascular plants?

4. Explain why nonvascular plants are usually found in moist shady areas.

Thinking Critically5. Explain why it is an advantage for mosses to

grow in mats or mounds composed of many individual plants.

6. Compare and Contrast the gametophyte andsporophyte generations of nonvascular plants.For more help, refer to Thinking Critically in theSkill Handbook.

SKILL REVIEWSKILL REVIEW

Figure 22.4 The upright sporophyte of thehornwort resembles an animal horn andgives the plant its name.

��

Sporophyte with sporangium (2n)

Gametophyte (n)

ReteachLinguistic Have studentsoutline the section and write

a definition for each vocabularyterm.

ExtensionNaturalist Have studentsprepare a key that will en-

able them to distinguish amongthe three divisions of nonvascularplants.

Portfolio Have studentsdraw plants from each division.Students should label the distin-guishing features on their draw-ings and place the drawings intheir portfolios.

4 CloseActivity

Interpersonal Have studentswrite three questions based

on the material covered in thissection. Have students read theirquestions while their classmatesprovide the answers.

P

LS

L2

P

LS

PP

LS

L1

P

LS


L3

P

LS

L2

P

LS

Section AssessmentSection AssessmentSection Assessment1. Thallose liverworts have a broad, ribbon-

like body that resembles a fleshy, lobedleaf. Leafy liverworts have three rows offlat, thin leaves attached to a stem.

2. The sporophyte generation is small andobtains food, water, and minerals fromthe larger gametophyte generation.

3. Nonvascular plants lack vascular tissue,

are typically small in size, have a domi-nant gametophyte generation, andgrow in moist, shady areas.

4. Since these plants rely on diffusion andosmosis for the transport of water andminerals, they tend to be found in areaswhere water is plentiful.

5. The dense mats retain water and helpreduce evaporation.

6. The gametophyte and sporophytegenerations are both stages of thenonvascular plant life cycle. Thesporophyte generation is smaller anddependent upon the gametophyte.The gametophyte generation is hap-loid and produces gametes, whereasthe sporophyte generation is diploidand produces spores.600


Reinforcement and StudyGuide, p. 97

Content Mastery, p. 110 L1

P

LS

L2

P

LS

Gametophyte (n)

Sporophyte (2n)

Section

What Is a Non-SeedVascular Plant?

The obvious difference between avascular and a nonvascular plant is thepresence of vascular tissue. As you mayremember, vascular tissue is made up oftubelike, elongated cells through whichwater and sugars are transported.Vascular plants are able to adapt tochanges in the availability of water, andthus are found in a variety of habitats.You will learn about three divisions ofnon-seed vascular plants: Lycophyta,Sphenophyta, and Pterophyta.

Alternation of generations Vascular plants, like all plants,

exhibit an alternation of generations.Unlike nonvascular plants, though,

the spore-producing sporophyte isdominant, Figure 22.5. The sporo-phyte is much larger in size than thegametophyte. The mature sporophyte

22.2 NON-SEED VASCULAR PLANTS 601

Imagine traveling back in timenearly 300 million years—50 mil-lion years before dinosaurs evolved.

As you look around Earth’s forests,you see a bewildering array of leafyvascular plants, some oddly familiar.Towering above the forest floor areincredibly tall, unusual-lookingtrees. Paleobotanists know whatthese ancient plants looked likebecause many were preserved asfossils. Living on Earth todayare plants that are reminiscentof these ancient vascular plants,including the club mosses, horse-tails, and ferns.

SECTION PREVIEW

ObjectivesExplain the importanceof vascular tissue to lifeon land.Identify the character-istics of the non-seedvascular plant divisions.

Vocabularystrobilusprothallusrhizomesorus

22.2 Non-Seed Vascular Plants

Figure 22.5In non-seed vascularplants, the sporo-phyte generation isdominant.

Tree fern and horsetails (inset)

601

Section 22.2

PrepareKey ConceptsThe non-seed vascular plant divi-sions Lycophyta, Sphenophyta,and Pterophyta are presentedalong with the traits that distin-guish these divisions from eachother.

Planning■ Obtain a glass tube and col-

ored water for the QuickDemo.

■ Purchase a resurrection plantfor the Enrichment.

■ Collect or purchase fernspores for the MiniLab.

■ Collect pictures of non-seedvascular plants for the Display.


P

ELL

LS

L1

P

LS



What type of environments do these two plants live in?

How are the structures of these two plants related totheir environments?

11

22

SECTION FOCUS

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Transparency Plants andTheir Environments53

Internet Address Book

Note Internet addresses that you find useful in the spacebelow for quick reference.

single vein of vascular tissue runsthrough each leaf. The stems of lyco-phytes may be upright or creepingand have roots growing from thebase of the stem.

The club moss, Lycopodium, is com-monly called ground pine because itis evergreen and resembles a minia-ture pine tree. Some species ofground pine have been collected fordecorative uses in such numbers thatthe plants have become endangered.

Adaptations inSphenophyta

Sphenophytes, or horsetails, repre-sent a second group of ancient vascu-lar plants. Like the lycophytes, earlyhorsetails were tree-sized membersof the forest community. There areonly about 15 species in existencetoday, all of the genus Equisetum.The name horsetail refers to thebushy appearance of some species.These plants are also called scouringrushes because they contain silica, an

abrasive substance,and were once used toscour cooking uten-sils. If you run yourfinger along a horse-tail stem, you can feelhow rough it is.

Today’s sphenophytes are muchsmaller than their ancestors, usuallygrowing to about 1 m tall. Mosthorsetails, like the one shown inFigure 22.8, are found in marshes,shallow ponds, stream banks, andother areas with damp soil. Somespecies are common in the drier soilof fields and roadsides. The stemstructure of horsetails is unlike mostother vascular plants; it is ribbed andhollow, and appears jointed. At eachjoint, there is a whorl of tiny, scale-like leaves.

Like lycophytes, sphenophytespores are produced in a strobilusthat is formed at the tip of somestems. After the spores are released,they may grow into a prothallus withantheridia and archgonia.


Figure 22.8 This is the sporophyte genera-tion of a horsetail, Equisetum.It has thin, narrow leaves thatcircle each joint of the slender,hollow stem. Plants with spo-rangia form a strobilus at thetips of some stems.

OriginWORDWORD

strobilus From the Greekword strobos, mean-ing “whirling.”Spore-bearingleaves form a com-pact cluster called astrobilus.

603

Visual LearningFigure 22.8 Point out that thestrobili at the tips of the horsetailstems are formed by leaves withspores. Have students use theappearance of the plant to specu-late as to why it was named ahorsetail. The plant looks roughlylike the tail of a horse.

EnrichmentKinesthetic Purchase a res-urrection plant (Selaginella

lepidophylla). Have students exam-ine the plant and decide if it isstill alive. Soak the plant in waterovernight and place it beneath aplant light. Have students ob-serve the plant again and con-sider if they should revise theiroriginal conclusion about wheth-er or not the plant is alive. L1

P

LS

does not depend on the gametophytefor water or nutrients.

A major advance in this group ofvascular plants was the adaptation ofleaves to form structures that protectthe developing reproductive cells. Insome non-seed vascular plants,spore-bearing leaves form a compactcluster called a strobilus (STROH bihlus). The spores are released from thestrobilus and then grow to form thegametophyte, called a prothallus(proh THAL us). The prothallus is rela-tively small and lives in or on the soil.The prothallus then forms antheridiaand archegonia, Figure 22.6. Spermare released from the antheridiumand swim through a continuous filmof water to the egg in the archego-nium. Fertilization occurs and a large,dominant sporophyte plant growsfrom the fertilized zygote.

Adaptations in Lycophyta

From fossil evidence it is knownthat tree-sized lycophytes were oncemembers of the early forest commu-

nity. Modern lycophytesare much smaller thantheir early ancestors.Lycophytes are com-monly called club mossesand spike mosses becausetheir leafy stems resem-ble moss gametophytes,and their reproductivestructures are clubshaped, as shown inFigure 22.7. However,unlike mosses, the sporo-phyte generation of thelycophytes is dominant.It has roots, stems, andsmall leaves. The leavesoccur as pairs, whorls, orspirals along the stem. A


archegonium

prothallus

antheridium

Figure 22.7Lycophytes are non-seed vascular plantswith roots, stems, andleaves, and spores pro-duced in a strobilus.

Figure 22.6Spores are released from a strobilusand grow into a prothallus. The pro-thallus forms antheridia and archego-nia. Sperm from the antheridia swimthrough a continuous film of water tothe egg in the archegonium, wherefertilization may then occur.

602

2 Teach


Stand a capillary tube in a petridish filled with colored water.Have students note the rise ofwater within the tube. Explainthat this movement occurs dueto capillary action. Ask studentsto correlate the movement ofwater in the glass tube to themovement of water in vascularplants. Use this demonstrationto explain the relationshipbetween the evolution of vascu-lar tissue and the increased sizeof plants, and the efficiency ofwater and mineral movementthroughout the plants.

P

LS

Skill Have students make aconcept map that illustrates themajor characteristics of Lyco-phytes, Sphenophytes, and Ptero-phytes.



English Language LearnersVisual-Spatial Pair students withlimited English proficiency and stu-

dents with strong English skills. Havethem review together the life cycle of vas-cular plants. Ask students to draw andlabel a diagram that illustrates alternationof generations.

P

COOP LEARN

LS

P

LSP

ELL

LS

L1

P

LS

PortfolioPortfolio

Horsetails Cross SectionVisual-Spatial Have students useinformation they have read about

horsetails to prepare what they believewould be cross-section diagrams of thestem of this plant. Have them add appro-priate labels to structures where needed.

P

LS

PP

LS

L2

P

LS


Spike and Club Moss QuestionLinguistic Have students write abrief essay to explain why club

mosses are not common in desert habitatsand why most people never see thegametophyte generation of these plants.Have students explain why these plantsare not related to the mosses that werediscussed in Section 22.1.

P

LS

L3

P

LS


Exploration: The Six KingdomsDisc 3

VIDEODISCSTV: PlantsWhat is a Plant?

Unit 1, Side 1, 3 min. 40 sec. Types of Plants

!84d5L$Ñ"


BioQuest: BioDiversity ParkDisc 3, 4



P

ELL

LS

L1

P

LS

Fern structures As with most vascular plants, it is

the sporophyte generation of the fernthat has roots, stems, and leaves. Thepart of the fern plant that we mostcommonly recognize is the sporo-phyte generation. The gametophytein most ferns is a thin, flat structurethat is independent of the sporo-phyte. In most ferns, the main stem isunderground, Figure 22.10. Thisthick, underground stem is called arhizome. It contains many starch-filled cells for storage. The leaves ofa fern are called fronds and growupward from the rhizome, as shownin Figure 22.11. The fronds areoften divided into leaflets called pin-nae, which are attached to a centralstipe. Ferns are the first of the vascu-lar plants to have evolved leaves withbranching veins of vascular tissue.

The branched veins in ferns trans-port water and food to and from allthe cells.


Figure 22.10Most ferns in warm climates areperennial plants that live from year toyear, gradually enlarging in size. Thefronds of ferns that live in temperateclimates die back during the winter.

Frond

Stipe

Rhizome

Pinnae

Figure 22.11Fern leaves are calledfronds. The fronds ofthe fern sporophytegrow from an under-ground rhizome.

The creeping, underground rhizome of a fern is a modified, condensed stem, with roots growing downward from each joint of stem and frond.

AA

A fern frond has a stem-like stipe and green,often finely divided leaf-lets called pinnae.

BB

Young fern fronds unfurl asthey grow and arecalled fiddleheadsbecause theirshape is similar to the neck of a violin.

CC

605

DisplayAdd pictures of non-seed vascularplants to the bulletin board dis-play.

Chalkboard ActivityLogical-Mathematical Askstudents to use information

about the number of plant speciesto prepare a bar graph. On thechalkboard, write the followinginformation.Bryophyta = 10 000Hepatophyta = 6500Anthocerophyta = 100Lycophyta = 1000Sphenophyta = 15Pterophyta = 12 000

Tell students that these num-bers represent the approximatenumber of living species for eachnon-seed plant division studiedso far. L2

P

LS

Adaptations inPterophyta

Ferns first appeared nearly 400million years ago according to thefossil record, at about the same timethat club mosses and horsetails werethe prominent members of Earth’splant population. Ferns, divisionPterophyta, grew tall and treelike,forming vast fern forests. You areprobably more familiar with fernsthan with club mosses and horsetails,primarily because ferns evolved intomany more species and are moreabundant. Ferns can be found inmany types of environments. You mayhave seen shrub-sized ferns such asthose pictured in Figure 22.9, on thedamp forest floor or along streambanks. Some ferns inhabit dry areas,becoming dormant when moisture isscarce and resuming growth andreproduction when water becomesavailable again. Explore the relation-ship between water and non-seedvascular plants in the Problem-SolvingLab on this page.

Is water needed for fertilization? Non-seed vascularplants have a number of shared characteristics. One of thesecharacteristics is related to certain requirements needed forreproduction.

AnalysisExamine the following data table. Notice that some of

the information is incomplete.

Thinking Critically1. How would you complete the column marked “Sperm

must swim to egg?”2. Explain how the column marked “Water needed for

fertilization” is related to answers in the previous column.3. Explain why the three plant divisions must all grow in the

same type of environment and what this environment is.4. What other means might be possible for plant sperm

delivery to eggs without the use of water?

Problem-Solving Lab 22-2Problem-Solving Lab 22-2 Applying Concepts

Division ExampleWater neededfor fertilization?

Sperm mustswim to egg?

Lycophyta

Sphenophyta

Pterophyta

club moss

horsetail

ferns

Data Table

Figure 22.9 There are about 12 000 species of living ferns. Ferns occupy widely diverse habitats and have a variety of different forms and sizes.

Most modern ferns are fairlysmall and leafy, but manyspecies of tall tree ferns stillexist, primarily in the tropics.

AA

This deer fern is foundonly in wet, shady, coastalevergreen forests.

BB

The bracken fern thrives in thepartial sun of open forests. Oneof the most common ferns in theworld, it often takes over largeareas of abandoned pasture oragricultural land.

CC

604

PurposeStudents will review the need forwater in the process of fertiliza-tion among certain plant divi-sions.

Process Skillsthink critically, acquire informa-tion, apply concepts, predict

Teaching Strategies■ Students will have to consulttheir text to determine the an-swers to the column marked“Sperm must swim to egg?” Youmay wish to advise them of thepage references to be used inresearching the answer.■ A “yes” or “no” answer is re-quired for the completion of bothcolumns.■ All correct answers should be“yes.”

Thinking Critically

1. yes to all2. Sperm can swim only in a

film of water. Therefore, thiscolumn must also be markedwith a yes.

3. Water is needed for fertiliza-tion. Therefore, these plantsmust grow in areas with suffi-cient moisture.

4. wind, insects, birds, mammals

Skill Ask students toreview the need for a film ofwater for fertilization of theBryophytes. With the answer inmind, have them hypothesize thegeneral environment surroundingthese plants millions of years ago.Use the Performance Task As-sessment List for Formulating aHypothesis in PASC, p. 21. L3

P

LS


P

LS

Problem-Solving Lab 22-2Problem-Solving Lab 22-2


Visually ImpairedKinesthetic Have visually impairedstudents examine a fern plant or

frond that has raised sori on the back ofthe frond. Have students feel the sori onthe back of the fronds. Ask students whatmakes up these groups of sori and if anyother vascular non-seed plants have thesestructures.

P

LSP

ELL

LS

L1

P

LS

VIDEODISCThe Secret of LifeLife Cycle of a Fern

!7;ELD"


Video: Fern DevelopmentDisc 3

P R O J E C TGrowing Fern Prothallia fromSpores

Kinesthetic Have students grow theirown fern prothallia by following the

procedure given. C-Fern spores and growingmedia are available from Carolina Biological(catalog #15-6700). Spores will germinate

within 5 days and prothallia within 8 to 12days. Students can design an experiment todetermine the effect of environment onspore germination and prothallia develop-ment. These cultures can be maintained andused to study fern reproduction in Chapter24.

P

LS

L3

P

LS


Laboratory Manual, pp. 153-156 L2

P

LS

million years ago, when it has beendetermined that Earth’s climatebecame cooler and drier. Today’snon-seed nonvascular plants aremuch smaller and less widespread intheir distribution than their prehis-toric ancestors.

The evolution of vascular tissueenabled these plants to live on landand to maintain larger body sizes incomparison with nonvascular plants.As you can tell from Figure 22.13,non-seed vascular plants are closelyrelated to nonvascular plants.



Understanding Main Ideas1. Why do most non-seed vascular plants live in

moist habitats?2. Compare and contrast the structure of lycophyte

and pterophyte sporophytes.3. What are the major differences between non-

seed vascular plants that exist today and thosethat lived in the Carboniferous forests?

4. How does the sporophyte of a vascular plant differ from the sporophyte of a nonvascularplant?

Thinking Critically5. Why do you think there are fewer non-seed vas-

cular plants on Earth today than there were 300million years ago?

6. Observing and Inferring How do you thinkthe presence of silica in the stems of sphenophytesmight protect these plants from being eaten by animals? For more help, refer to ThinkingCritically in the Skill Handbook.


PRESENT CENOZOIC PALEOZOIC PRECAMBRIANMESOZOIC

Sphenophytes15 species

Lycophytes1000 species

��

��

Psilophytes30 species

Pterophytes12 000 species

Protists

Bryophytes20 000 species

Anthocerophytes100 species

Hepatophytes6500 species

Lepidodendron

Calamites

Figure 22.13The relationships of divisions of non-seed vascular plants on the GeologicTime Scale show that they are closelyrelated to the nonvascular plants.

PLANTS

3 AssessCheck for UnderstandingHave students explain how theterms in each of the followinggroups are related.

a. strobilus—sphenophytesb. prothallus—gametophyte—

fernc. sporophyte—dominant—

lycophytes

ReteachHave students list three char-acteristics for each division: Lycophyta, Sphenophyta, andPterophyta.

ExtensionVisual-Spatial Have studentsmake a concept map to

explain the changes in size in thesporophyte and gametophytegenerations of Bryophyta, Lyco-phyta, and Pterophyta.

Knowledge Provide stu-dents with unlabeled photos ordrawings of gametophytes andsporophytes from each of the non-seed vascular divisions. Have stu-dents identify each picture.

4 CloseDiscussion

Naturalist Ask students tocompare the gametophyte

generations of mosses and ferns.Moss is large and green; fern issmall and green. Have them do thesame for the sporophyte genera-tion. Moss is small and nongreen;fern is large and green.

P

LS

L1

P

LS

L2

P

LS


L3

P

LS

L1

P

LS

P

ELL

LS

L2

P

LS

The fern life cycle is representativeof other non-seed vascular plants.Fern spores are produced in struc-tures called sporangia.

Clusters of sporangia form a struc-ture called a sorus (plural, sori). Thesori are usually found on the under-sides of the pinnae, Figure 22.12,but in some ferns, spores are borneon whole, modified fronds. Practiceyour lab skills and learn more aboutfern spores and sporangia in theMiniLab on this page.

Origins of Non-SeedVascular Plants

The earliest evidence of non-seedvascular plants is found in fossilsfrom the early Paleozoic period,around 390 million years ago. Largetree-sized lycophytes, sphenophytes,and pterophytes were extremelyabundant in the warm, moist foreststhat dominated Earth during theCarboniferous period. Ancient lyco-phyte species grew as tall as 30 m.Many of these species of non-seedvascular plants died out about 280


Identifying Fern Sporangia Whenyou admire a fern growing in a garden or forest, you are admiringthe plant’s sporophyte generation.Upon further examination, youshould be able to see evidence ofspores being formed. Typically, the evi-dence you are looking for can be found on the underside of the ferns’ fronds.

Procedure ! Place a drop of water and a drop of glycerin at opposite

ends of a glass slide.@ Use forceps to gently pick off one sorus from a frond.

Place it in the drop of water and add a cover slip.# Add a second sorus to the glycerin and add a cover slip.$ Observe both preparations under low-power magnifica-

tion and note any similarities and differences. Look forlarge sporangia (resembling heads on a stalk) and spores(tiny round bodies released from a sporangium). CAUTION: Use caution when working with a microscope,microscope slides, and cover slips.

Analysis1. Were spores more visible in water or in glycerin?2. What did the glycerin do to the sporangium?3. Formulate a hypothesis that may explain how sporangia

naturally burst.4. Formulate a hypothesis that may explain how sporangia

were affected by glycerin.

MiniLab 22-1MiniLab 22-1

Figure 22.12Sori found on the undersideof fern fronds look like brownor rust-colored dust.

Fern sporangium

Experimenting

Most sori are found asround clusters on the pinnae. The shape of theclusters and arrangementon the pinnae vary withspecies.

AA

Some species of fernshave sori on the edgesof the pinnae, such asthis Osmunda fern.

BB

606

PurposeStudents will observe the releaseof spores from a sporangium.

Process Skillscompare and contrast, hypothe-size, observe and infer

Teaching Strategies■ Ferns with sori may beobtained from a biological supplycompany.■ Glycerin will cause sporangiato enlarge and break open,releasing spores. This event canbe observed by students if theyexercise a little patience whileviewing the sporangia under themicroscope. Glycerin will causeboth fresh and preserved sporan-gia to break open.■ Use of a single-edged razorrather than a forceps to lift soriwill reduce the amount of rup-ture to the sporangia. Cautionstudents to use care when work-ing with a razor blade.

Expected ResultsStudents will see a few sporesreleased from sporangia underwater but should see many morein glycerin.

Analysis1. glycerin2. Glycerin caused the sporan-

gia to break open.3. Student answers may vary—

drying out of sporangium,absorption of water.

4. Student answers may vary—glycerin causes osmotic im-balance.

Knowledge Ask studentsto describe the events that wouldfollow the release of fern spores.Use the Performance TaskAssessment List for Events Chainin PASC, p. 91. L2

P

LS


P

LS


Section AssessmentSection AssessmentSection Assessment1. Sperm cells must be able to swim

through a continuous film of water tofertilize egg cells within the archego-nia.

2. Lycophytes are small, grow close tothe ground, and have stems coveredby small, narrow leaves. Roots, stems,and leaves are present. Pterophytesalso have roots, stems, and leaves. The

stem is underground. Leaves calledfronds are usually finely divided intopinnae. Spores are found within sorion the undersides of the fronds.

3. Ancient species were much larger insize and more abundant.

4. The sporophyte of a vascular plant islarger and is not dependent on thegametophyte generation.

5. Earth’s climate has changed, reducingthe number of damp areas in whichnon-seed vascular plants could sur-vive.

6. The silica in the stems would be hardfor predators to digest. It might alsocut the delicate tissues of their diges-tive tracts.

607

Resource ManagerResource ManagerBioLab and MiniLab Worksheets,

p. 101Reinforcement and Study Guide,

pp. 98-99Content Mastery, p. 110 L1

P

LS

L2

P

LS

L2

P

LS

MiniLab 22-2MiniLab 22-2 Comparing and Contrasting

Figure 22.14Seeds exhibit a variety ofstructural adaptations.

the young diploid sporophyte of theplant. Embryos of seed plants includeone or more cotyledons. Cotyledonsare tiny seed leaves that store orabsorb food for the developingembryo. In conifers and many flow-ering plants, cotyledons are theplant’s first leaves when it emergesfrom the soil.

Advantages of seedsA seed consists of an embryo and

its food supply enclosed in a tough,protective coat, Figure 22.14. Seedplants have several important advan-tages over non-seed plants. The seedcontains a supply of food to nourishthe young plant during the earlystages of growth. This food is usedby the plant until its leaves are devel-oped enough to carry out photosyn-thesis. In conifers and some flower-ing plants, the food supply is storedin the cotyledons. The embryo isprotected during harsh conditions bya tough seed coat. The seeds of manyspecies are also adapted for easy dis-persal to new areas, so the youngplant does not have to compete withits parent for sunlight, water, soilnutrients, and living space. You canlearn more about seed structure inthe MiniLab shown here.

The pine embryo includesseven to nine cotyledons,which serve as an initial foodsupply when growth begins.

AA

The feathery tuftattached to milkweedseeds aids in their dispersal.

CC

The tough protective seedcoat breaksdown whengrowthbegins.

BB

Comparing Seed Types Anthophytes are classified into twoclasses, the monocotyledons (monocots) and dicotyledons(dicots) based on the number of seed leaves.

Procedure! Copy the data table shown below.@ Examine the variety of seeds given to you. Use forceps to

gently remove the seed coat or covering from each seed ifone is present.

# Determine the number of cotyledons present. If two cotyle-dons are present, the seed will easily separate into twoequal halves. If one cotyledon is present, it will not separateinto halves. Record your observations in the Data Table.

$ Add a drop of iodine stain to rice and a lima bean seed.Note the color change. CAUTION: Wash your hands withsoap and water after handling chemicals. Record yourobservations in the Data Table.

Analysis1. Starch turns purple when iodine is added to it. Describe

the color change when iodine was added to rice and limabean seeds.

2. Hypothesize why seeds contain stored starch.

Seed nameColor with iodine

Monocotor dicot

Number ofcotyledons

Lima bean

Rice

Pea

Rye

——

——

Data Table

609

609

2 Teach

PurposeStudents will determine how totell if a seed is from a monocot ordicot plant and test for the pres-ence of starch in seeds.

Process Skillsacquire information, apply con-cepts, classify, compare and con-trast, predict

Teaching Strategies■ Presoak all seeds overnight sothat seed coats come off easily.■ Supply single-edged razorblades to remove seed coats.■ Seeds are available from gro-cery stores, hardware stores (rye),or pet shops (bird feed).■ Use a dilute iodine solutionwhen testing for starch (3 gpotassium iodide and 1 g iodineto 300 mL of water). Place indropper bottles for ease in stu-dent dispensing. Caution stu-dents that iodine is toxic and aneye irritant. If it is spilled on skinor clothing it should be washedimmediately.

Expected ResultsThe lima bean, pea, and sun-flower are dicots. All others aremonocots. Rice and lima beanswill turn blue.

Analysis1. The seeds turn purple.2. Starch supplies a growing

embryo with food.

Portfolio Have studentsdiagram the lima bean seeds theydissected and color in the areathat stained purple. Ask studentsto write a paragraph about theadvantages of seed productionbeneath their diagram and placetheir work in their portfolios. Usethe Performance Task AssessmentList for Scientific Drawing inPASC, p. 55. PP

LS

L2

P

LS


P

LS


Section


What Is a Seed Plant?Some vascular plants produce

seeds, which are reduced sporophyteplants enclosed within a protectivecoat. The seeds may be surroundedby a fruit or carried naked on thescales of a cone.

Seed plants produce sporesIn seed plants, as in all other

plants, spores are produced by thesporophyte generation. These sporesdevelop into the male and femalegametophytes. The male gameto-phyte develops inside a structurecalled a pollen grain that includessperm cells, nutrients, and a protec-tive outer covering. The femalegametophyte, which produces theegg cell, is contained within a sporo-phyte structure called an ovule.

Fertilization and reproductionThe union of the sperm and egg

forms the sporophyte. In most seedplants, this process, called fertiliza-tion, does not require a continuouslayer of water for fertilization, as dononvascular and non-seed vascularplants. Remember that in non-seedplants, the sperm must swim througha continuous film of water in order toreach the egg in the archegonia of agametophyte. Because they do notrequire a continuous film of water forfertilization, seed plants are able togrow and reproduce in a wide varietyof habitats that have limited wateravailability.

After fertilization, the zygotedevelops into an embryo. An embryois an organism at an early stage ofdevelopment. In plants, an embryo is

About 280 million years ago, when club mosses, ferns, andother non-seed plants had

reached their greatest numbers anddiversity, it has been shown in rocks that Earth’s climate changed. Freezingweather and drought may havecaused many non-seed plants tobecome extinct, but a few of theseed plants were adapted tothese extreme conditions andthey were able to survive.These ancient survivors arethe ancestors of today’s vascu-lar seed plants.

SECTION PREVIEW

ObjectivesIdentify the character-istics of seed plants.Analyze the advan-tages of seed and fruitproduction.

Vocabularypollen grainovuleembryocotyledonfruit deciduous plantmonocotyledonsdicotyledonsannualsbiennials perennials

22.3 Seed Plants

Anthophyte fruitsand seeds andconiferophytecones and seeds(inset)

608

Section 22.3

PrepareKey ConceptsThe major characteristics of seed plants are examined. The fivedivisions described are Cycado-phyta, Ginkgophyta, Gnetophyta,Coniferophyta, and Anthophyta.

Planning■ Collect seeds for the MiniLab.■ Collect pictures of seed plants

for the Display.■ Collect examples of monocot

and dicot leaves for the VisualLearning.

■ Collect gardening books andseed/flower catalogs for theTech Prep Activity.


P

ELL

LS

L1

P

LS



Transparency Gymnosperm Cones54 SECTION FOCUS

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

How are these cones similar?

What is their function?

11

22

Douglas fir

Monterey cypress

Ponderosa pine

Juniper

Brewer spruce

Internet Address Book

Note Internet addresses that you find useful in the spacebelow for quick reference.

Cultural DiversityImportance of Non-flowering Seed Plants

Linguistic Many species of non-flower-ing seed plants play significant roles as

timber trees, food plants, and sources ofessential oils and soaps in the economies ofcountries. Initiate a discussion about the cul-tural importance of the ginkgo tree in Chinaand Japan. Ginkgo biloba is the only living

representative of the Ginkgophyta divisionand no longer exists in the wild. It has beencultivated for thousands of years for use asan ornamental plant in Chinese and Japanesetemple gardens. Have students choose differ-ent types of non-flowering seed plants andpresent reports on their economic value orcultural significance in different countries.P

LS

L3

P

LS

Adaptations inGnetophyta

Most living gnetophytes can befound in the deserts or mountains ofAsia, Africa, North America, andCentral or South America. The divi-sion Gnetophyta contains only threegenera, which are all different instructure and adaptations. The genusGnetum is composed of tropicalclimbing plants. The genus Ephedracontains shrublike plants and is theonly gnetophyte genus found in theUnited States. The third genus,Welwitschia, is a bizarre-looking plantfound only in South Africa. It growsclose to the ground, has a largetuberous root, and may live 100years. Ephedra and Welwitschia arepictured in Figure 22.17.

Adaptations inConiferophyta

The sugar pine is one of manyfamiliar-looking forest trees thatbelong to the division Coniferophyta.The conifers are trees and shrubswith needle- or scalelike leaves. They

are abundant in foreststhroughout the world, andinclude pine, fir, spruce, juniper,cedar, redwood, yew, and larch. A fewrepresentative conifers are shown inFigure 22.18. Think of ways thatyou could distinguish among the dif-ferent species of conifers in theBioLab at the end of this chapter.

22.3 SEED PLANTS 611

Figure 22.17Most gnetophytes have separate male and female plants.

Figure 22.18Conifers are namedfor the woody conesin which the seeds ofmost species develop.

Members of thegenus Ephedra are asource of ephedrine,a medicine used totreat asthma, emphy-sema, and hay fever.

AA

The Douglas fir is oneof the most importantlumber trees in NorthAmerica. It growsstraight and tall, to aheight of 100 m.

AA

Spruce trees are popularornamental trees becauseof their graceful shape andcolor variations.

BB

Welwitschia may live100 years. The planthas only two leaves,which continue tolengthen as theplant grows older.

BB

611

Concept DevelopmentAsk students to compare andcontrast Gnetophyta with Gink-gophyta. As a means for doingthis, have students prepare achart with the headings “Gne-tophyta and Ginkgophyta Sim-ilarities” and “Gnetophyta andGinkgophyta Differences.” Havestudents include comparisons ofreproductive structures as well asgeneral traits. Ask them also toinclude where each plant is foundin the world, the number ofspecies alive today, the number ofgenera present today, and eco-nomic uses of these plants.

EnrichmentIntrapersonal The drug eph-edrine has been used by the

Chinese for more than five thou-sand years. It is called ma huang,which means “astringent and yel-low.” The words refer to thedrug’s taste and color. Ephedrinedecreases smooth and cardiacmuscle action, raises blood pres-sure, dilates the pupils, andreduces congestion. Have inter-ested students research this drugand write a report on its uses andits source. L3

P

LS

L2

P

LS

Diversity of seed plantsSome plants produce seeds on the

scales of woody strobili called cones.This group of plants is sometimesreferred to as gymnosperms. The termgymnosperm means "naked seed" andis used with these plants because theyare not protected by a fruit. The gym-nosperm plant divisions you will learnabout are Cycadophyta, Ginkgophyta,Gnetophyta, and Coniferophyta.

Flowering plants, also calledangiosperms, produce seeds enclosedwithin a fruit. A fruit is the ripenedovary of a flower. The fruit providesprotection and aids in seed dispersal.The Anthophyta division contains allspecies of flowering plants.

Adaptations inCycadophyta

About 100 species of cycads existtoday, exclusively in the tropics andsubtropics. The only present-dayspecies that grows wild in the UnitedStates is found in Florida, althoughyou may see cycads cultivated ingreenhouses or botanical gardens, asshown in Figure 22.15.

All cycads have separate male andfemale plants. The cones of maleplants produce pollen. The cones offemale plants produce seeds. Cycadsare one of the few seed plants thatproduce motile sperm. The trunksand leaves of many species resemblepalm trees, but cycads are not closelyrelated to palms, which are antho-phytes.

Adaptations inGinkgophyta

Like cycads, ginkgos produce maleand female reproductive structureson separate plants. The male ginkgoproduces pollen in strobiluslike conesthat grow from the bases of leaf clus-ters. The female ginkgo produces theseeds, which develop a fleshy, apri-cot-colored seed coat that covers theseeds as they ripen, Figure 22.16.Ginkgos are often planted in urbanareas because they are able to toleratesmog and pollution. Gardeners andlandscapers usually prefer the maletrees because the fleshy seed coat onseeds produced by the female trees hasan unpleasant smell.

Today, the division is representedby only one living species, Ginkgobiloba. The ginkgo tree is consideredsacred in China and Japan, and hasbeen cultivated in temple gardens forthousands of years. These Asian tem-ple gardens probably prevented thetree from becoming extinct.

Figure 22.16The seeds of the femaleginkgo develop a fleshy outercovering (a). The ginkgo issometimes called the maiden-hair tree because its lobedleaves resemble the fronds ofa maidenhair fern (b).

Figure 22.15Cycads have a termi-nal rosette of leaves.The male plant hascones that producepollen grains that arereleased in greatmasses into the air(a). The female plantproduces cones thatcontain ovules witheggs (b).

b

a

a

b610

610


Visual-Spatial Providestudents with a variety

of cones. Ask them to describewhat might be found withinor upon each wooden scale.Some students may say seeds.Have them gently pry thescales open to reveal the seedswithin.

P

ELL

LS

L1

P

LS


Is It a Cycad?Logical-Mathematical Have studentsimagine that they are traveling

through Florida with a friend. Their friendidentifies a plant as a cycad that is formingseeds. They search the surrounding area formore cycads but find none within a 20-kilo-meter radius. Have students write in theirjournals as many reasons as possible to

explain why they believe their friend incor-rectly identified the plant as a cycad. Cycadsare either male or female; therefore, themale plant must be close to the female toprovide pollen. Palms can self-fertilize—being both male and female—and can growalone and reproduce. Thus it is likely thatthis plant was a palm.

P

LS

L2

P

LS


GiftedLinguistic Have students use refer-ences to determine and record the

scientific names for all conifers listed inthis section. Have them describe the traitsthat are represented in the scientificnames.

P

LS

L3

P

LS

VIDEODISCSTV: PlantsWhat Is a Seed?

Unit 4, Side 3, 13 min. 45 sec.What Is a Seed?

!7,W=9LÇ"

Knowledge Have studentsconstruct a table that includes thefive divisions of seed plants andtheir major characteristics. L2

P

LS



Exploration: Classifying PinesDisc 3Video: Giant RedwoodsDisc 3



BioLab and MiniLab Work-sheets, p. 102

Critical Thinking/ProblemSolving, p. 22 L3

P

LS

L2

P

LS

P

ELL

LS

L1

P

LS

Stoma

Pine needlebundles

EpidermisEndodermisResin duct


Pine Needles

When you look at a snow-covered pine forest, you maybe surprised to learn that winter can be considered a

dry time for plants. The cold temperature means that the soilmoisture is unavailable because it is frozen. The needles of pineshave several adaptations that enable the plants to conservewater during the cold dry winter and the dry heat of the summer.

Critical Thinking How do the shape and structure of pine needles enable conifers to survive hot and dry summers as wellas cold and snowy winters?

INSIDESSTORTORYY

INSIDE

Resin ducts Resinis secreted from resinducts in the leavesand bark. It protectsthe tree from insects.

33Modified epidermis The epidermishas two modifications that are impor-tant in reducing water loss. The wallsof the epidermal cells are very thickand the epidermis is covered with awaterproof waxy cuticle.

22

Snow-covered pines

Bundles of needles The thick,leathery needles of many speciesof pine grow in bundles of two,three, or five. The cylindrical nature of these bundles, as well as their flexibility,causes snow and ice to slide off the needles more easily.

55

Shape reduces water lossPine needles are usually semicir-cular or round. This shapereduces the surface area. Lesswater is lost to evaporationbecause of the smaller surfacearea from which it can evaporatecompared with the large surfacearea of broad-leaf tree leaves,such as a maple.

11

Recessed stomata The stomata arerecessed into the epidermal layer, theoutermost layer of plant tissue. This posi-tion helps retain water in the leaf tissues.

44

PurposeStudents examine the adaptationsthat enable conifers to survive inharsh environments.

Teaching Strategies■ Have students describe com-mon everyday structures or ob-jects that are analogous tostructures found in pine needles.Students may correlate cuticle to waxpaper, or stomata to skin pores.

Visual LearningHave students examine a pre-pared slide of the cross section ofa pine needle.

Critical ThinkingPine needles have several struc-tural adaptations that reduceevaporation. These features helpconifers survive times when wateris scarce.

P

ELL

LS

L1

P

LS

L2

P

LS

P

LS

Analysis1. How does the cross-section view of a

conifer leaf differ from what you wouldsee in a deciduous tree leaf? round ratherthan flat and long

2. What may be the role of the normallygreen mesophyll and palisade layers?responsible for food production

3. What is the function of the cuticle andvascular tissue? retain water, transportmaterials

Skill Diagram or describe how across-section slice of a conifer leaf would bemade. Use the Performance Task Assess-ment List for Model in PASC, p. 51. L2

P

LS


613

The reproductive structures ofmost conifers are produced in cones.Most conifers have male and femalecones on different branches of the

same tree. The male cones producepollen. They are small and easy tooverlook. Female cones are muchlarger. They stay on the tree until theseeds have matured. Examples ofboth types of cones are shown inFigure 22.19.

Conifers are evergreensMost conifers are evergreen plants,

that is, they retain their leaves allyear. Although individual leaves dropoff as they age or are damaged, thetree never loses all its leaves at once.Pine needles, for example, mayremain on the tree for anywherefrom two to 40 years, depending onthe species.

Trees that retain their leaves beginphotosynthesis in the early spring assoon as the temperature warms.Evergreen leaves usually have a heavycoating of cutin, an insoluble waxymaterial. Evergreens are often foundwhere the warm growing season isshort, so keeping leaves year-roundgives them a head start on growth.Because they do not need to producea whole new set of leaves each year,they are able to grow where nutrientsare scarce. How do the needlelikeleaves of pines prevent water loss? Tofind out read the Inside Story.

Deciduous trees lose their leavesA few conifers, including larches

and bald cypress trees, are deciduous,Figure 22.20. Deciduous plantslose all their leaves at the same time.Dropping all leaves is an adaptationfor reducing water loss when water isunavailable as it can be the case inthe tundra, in deserts, or during win-tertime. Plants lose most of theirwater through the leaves; very little islost through bark or roots. However,a tree with no leaves cannot photo-synthesize and must remain dormantduring this time.


OriginWORDWORD

deciduous From the Latinword deciduus,meaning to “falloff.” Deciduoustrees drop all oftheir leaves at thesame time.

Figure 22.19Each scale of a conifer’s coneis a modified branch.

In many conifers,including the pine fam-ily, two seeds developat the base of each ofthe woody scales thatmake up a female cone.

BB

Male cones are madeup of thin paperyscales that open toshed clouds of yellowpollen grains into the wind.

AA

Figure 22.20Some trees, includingthese bald cypresstrees, lose their leavesin the fall as an adap-tation for reducingwater loss.

DisplayAdd pictures of seed plants to thebulletin board.

Chalkboard ActivityVisual-Spatial Have studentsconstruct a time line that

marks the era when differenttypes of land plants evolved. Askstudents to describe what the cli-mate was like during each timeperiod. L2

P

LS

Alternative LabThe Conifer Leaf

PurposeStudents will observe, diagram, and labelthe structures of a typical conifer leaf.Materialsmicroscope, prepared slide of conifer leafcross section.

P

LS

ProcedureGive students the following directions.

1. Observe the slide under low power.2. Diagram what you see. Label the

following structures using thesedescriptions as a guide: (a) cuticle—noncellular layer, thin covering overleaf; (b) epidermis—below cuticle, onecell in thickness; (c) mesophyll (spongylayer)—large cells, thick layer justbelow epidermis; (d) endodermis—

one-cell-layer thick, surrounds largeoval central area; (e) palisade layer—many cells in thickness, surrounded byendodermis; (f) vascular tissue—verycenter of leaf, two types are present.

3. Look again at the leaf using the micro-scope. Check for evidence of stomataon the epidermis and the presence ofseveral ringlike parts, called resinducts, in the mesophyll. Add theseparts and labels to your diagram.612

IINSIDENSIDESSTORTORYY

INSIDE

The BioLab at theend of the chaptercan be used at thispoint in the lesson.

YOUR OWNDESIGN

YOUR OWNDESIGN

dicotyledons. The two classes arenamed for the number of seed leaves,or cotyledons, contained within theseed. Monocotyledons have oneseed leaf; dicotyledons have twoseed leaves. The names of these twoclasses are often abbreviated tomonocots and dicots. Monocots arethe smaller group, with about 60 000identified species that include fami-lies such as grasses, orchids, lilies,and palms, Figure 22.23. Dicotsmake up the majority of floweringplants with about 170 000 identifiedspecies. They include nearly all thefamiliar shrubs, trees (exceptconifers), wildflowers, garden flow-ers, and herbs. Familiar dicots areshown in Figure 22.24.

Life spans of anthophytesWhy do some plants live longer

than people, and others live only afew weeks? The life span of a plantreflects its strategies for survivingperiods of cold, drought, or otherharsh conditions.

Annual plants live for only a yearor less. They sprout from seeds,

grow, reproduce,and die in a singlegrowing season. Mostannuals are herbaceous, which meanstheir stems are green and do not con-tain woody tissue. Many food plantssuch as corn, wheat, peas, beans, andsquash are annuals, as are manyweeds of the temperate garden.Annuals form drought-resistant seedsthat survive the winter.


Figure 22.23Monocots usually have leaveswith parallel veins and flowerparts in multiples of three.

Figure 22.24Dicots usually have leaves withbranched veins and flower partsin multiples of four or five.

The grass family includesimportant cereal grains,such as rice and wheat, aswell as sugarcane (left)and bamboo.

AA

The lily familyincludes aspara-gus and onionsas well as theornamental lilies(left) grown by many homegardeners.

BB

The daisy familyincludes sunflowers(above), lettuce, dandelions, chrysan-themums, and gold-enrod.

CC

The rose family includes blackberries(below), raspberries, apples, plums,peaches, pears, and hundreds of cul-tivars of garden roses.

BB

The mustard familyincludes many importantfood plants, such ascabbage, mus-tard, broccoli(shown here in flower),radish, turnip,collards, andkale.

AA

615

Visual LearningShow students examples of com-mon monocot and dicot leaves.Ask students how the vein pat-terns in dicot leaves differ fromthose of monocots.

Knowledge Have studentsdiscuss the adaptive value ofannual, biennial and perennial lifespans. L2

P

LS


discover in Biology & Society at theend of this chapter, different groupsof people have different viewpointson preserving this rich habitat.

Fruit productionAnthophytes are unique in that

they are the only division of plantsthat produce fruits, the ripened ovaryof a flower. A fruit may contain one ormore seeds. One of the advantages offruit-enclosed seeds is the added pro-tection the fruit provides for the youngembryo. Fruits often aid in the disper-sal of seeds. Animals may eat them orcarry them off to store for food. Seedsof some species that are eaten maypass through the animal’s digestivetract unharmed and are distributed asthe animal wanders. In fact, someseeds must pass through a digestivetract before they can begin to grow anew plant. Some fruits have structuraladaptations that help disperse the seedby wind or water. Some examples offruits are illustrated in Figure 22.22.

Monocots and dicotsThe division Anthophyta is divided

into two classes: monocotyledons and


Figure 22.22Fruits exhibit a widevariety of structuraladaptations that aidin seed protectionand dispersal.

Figure 22.21A florist’s display is agood place to see anassortment of flower-ing plants. How manycan you recognize?

Adaptations inAnthophyta

Flowering plants are classified inthe division Anthophyta and are themost well-known plants on Earthwith more than 240 000 identifiedspecies. See if you are familiar withsome of the plants in Figure 22.21.Like other seed plants, anthophyteshave roots, stems, and leaves. Butunlike the other seed plants, antho-phytes produce flowers and formseeds enclosed in a fruit. Many dif-ferent species of flowering plantsinhabit tropical forests. As you will

The fruit of a magnolia containsmany seeds surrounded with abright red covering that attractsbirds and small animals.

BB

The tough fibrousfruit of a coconutprovides protectionas well as a flota-tion device.

CC

AA The maple seed hasa winglike structurethat helps keep it

airborne.

614

Designing a GardenHave students in groups designthe layout of a flower gardenfor the schoolyard or a localpark. They should start by mea-suring the space and making ascale diagram. Using gardeningbooks and flower/seed catalogs(using the library or the Inter-net), they can choose appropri-ate plants for their garden. Thegarden should include annualsand perennials as well as a fewflowering shrubs or trees. Stu-dents can select plants for spe-cific locations based on sizeand flower color.

P

COOP LEARN

LS

P

LSP

ELL

LS

L2

P

LS

PortfolioPortfolio

Seed Dispersal MethodsVisual-Spatial Students should col-lect and identify pictures of seeds

from many different types of seed plants.The students should label each picturewith how they think the seeds are dis-persed.

P

LS

PP

LSP

ELL

LS

L1

P

LS


Exploration: AngiospermDisc 3Video: Blooming FlowersDisc 3Resource

ManagerResource Manager

Concept Mapping, p. 22

Laboratory Manual, pp. 157-160 L2

P

LS

P

ELL

LS

L3

P

LS

Origins of Seed PlantsSeed plants first appear as fossils

360 million years ago. Some seedplants, such as cycads and ginkgos,shared Earth’s forests with thedinosaurs during the Triassic andCretaceous periods. However, likethe dinosaurs, most members of theGinkgophyta died out about 66 mil-lion years ago.



Understanding Main Ideas1. Name two ways that seeds help plants reproduce

on land.2. How are needlelike leaves an adaptation to life

in climates where water may be limited?3. Why are flowering plants so successful?4. What are the major characteristics of anth-

ophytes that distinguish them from conifero-phytes?

Thinking Critically5. How do you think the development of the seed

might have affected the lives of herbivorous ani-mals living in Earth’s ancient forests?

6. Compare and Contrast Compare the forma-tion of a spore in ferns and a seed in conifers. Formore help, refer to Thinking Critically in the SkillHandbook.


PRESENT CENOZOIC PALEOZOIC PRECAMBRIANMESOZOIC

Cycads100 species

Conifers550 species

Anthophytes240 000 species

Protists

Seed ferns

Ginkgos1 species

Gnetums70 species

Figure 22.26The relationships of divisions of seedplants on the Geologic Time Scaleshow that the seed plant divisionsare closely related to each other.

According to fossil evidence, thefirst conifers emerged around 280million years ago. During the Jurassicperiod, conifers became prominentforest inhabitants and remain so today.

Anthophytes first appear in theearly Cretaceous period.

Seed plants are closely related toeach other and to other groups ofnon-seed vascular plants as shown inFigure 22.26.

PLANTS

617

ReteachHave students name plants thatare examples of each of the termslisted in Check for Understand-ing.

ExtensionVisual-Spatial Have studentsprepare an illustrated report

that depicts uses for five types ofnon-flowering seed plants. Havestudents identify each plant withits common and scientific name.

Skill Have students pre-pare questions about the charac-teristics of seed plants. Askstudents to read their questionsaloud and have the class providethe answers.

4 CloseDiscussionHave students describe the adap-tations for survival that are exhib-ited by seed plants in a landenvironment. L2

P

LS

L2

P

LS


L3

P

LS

L1

P

LS

Section AssessmentSection AssessmentSection Assessment1. Seeds contain a food supply for the devel-

oping embryo and protect the embryofrom harsh conditions.

2. The thick cuticle, reduced surface area,and sunken stomata limit evaporation.

3. Flowering plants produce fruits that pro-tect the seeds and aid in seed dispersal.

4. Anthophytes produce flowers and fruits.Coniferophytes do not.

5. By eating seeds, herbivores were able totake advantage of the food supplyintended for the young plant embryo.

6. Fern spores are produced in sporangia.Clusters of sporangia form sori that arefound on the pinnae. Conifer seeds areproduced on the scales of the cone.

Biennials have a life span that laststwo years. Many biennials are plantsthat develop large storage roots, suchas carrots, beets, and turnips. Duringthe first year, biennials grow manyleaves and develop a strong root sys-tem. Over the winter, the abovegroundportion of the plant dies back, butthe roots remain alive. Undergroundroots are able to survive conditionsthat leaves and stems cannot endure.During the second spring, food storedin the root is used to produce newshoots that produce flowers and seeds.

Perennials live for several years,producing flowers and seeds periodi-cally—usually once each year. Theysurvive harsh conditions by droppingtheir leaves or dying back to soillevel, while their woody stems orunderground storage organs remainintact and dormant. Examples ofplants with different lifespans areshown in Figure 22.25.


CAREERS IN BIOLOGY

Lumberjack

I f you like to spend time in the forest, consider a career as a

lumberjack or a logging industryworker. Besides being outdoors,you will get lots of exercise.

Skills for the JobThe logging industry now includes

many different workers. Cruisers choosewhich trees to cut. Fallers use chainsaws andaxes to cut or "fell" the chosen trees. Buckers saw off thelimbs and cut the trunk into pieces. Logging supervisors over-see these tasks. Other workers turn the tree into logs orwood chips that are used to make paper. After finishing highschool, most loggers learn on the job. However, with a two-year degree, you can become a forest technician. A four-yeardegree qualifies you as a professional forester who managesthe forest resources. Most logging jobs are in the Northwest,Northeast, South, and Great Lakes regions.

For more careers in related fields, be sureto check the Glencoe Science Web Site.

www.glencoe.com/sec/science.

Figure 22.25Anthophytes may beannuals, biennials, orperennials.

Vegetable garden-ers grow biennialSwiss chard for itsleaves.

AA

Herbaceous perennialsoften have undergroundstorage organs used foroverwintering.

DD

These blue lupinesand orange poppiesare annual plants.

CC

Woody perennials, like this maple,drop their leaves and become dor-mant during the winter.

BB

616

Career PathCourses in high school:mathematics, electronics,

shop courses involving machineryCollege: courses in forestry orlogging; two-year degree tobecome a forest technicianOther education sources: on-the-job training

Career IssueSome groups are trying to stoplogging, especially in old-growthforests. Discuss whether studentsthink most lumberjacks and otherlogging industry workers areconcerned about the future of theforests.

For More InformationFor more information aboutworking in the logging industry,students can write to:

Society of American Foresters5400 Grosvenor LaneBethesda, MD 20814

3 AssessCheck for UnderstandingHave students explain the dif-ferences between: fruits andcones; deciduous and evergreen;monocot and dicot; annual andperennial; and gymnosperm andangiosperm. L2

P

LS

CAREERS IN BIOLOGY

Tree FarmsTree farms allow foresters to meet increaseddemands for wood and wood products andreduce the demand for trees from naturalforests. Some people oppose this monoculturetechnique. Monoculture refers to the practiceof growing only one species of tree.

Monocultures are susceptible to insect pestsand diseases. Have interested students re-search the types of trees harvested by fores-ters in their region of the United States. Askstudents to find out if any of these trees aregrown in monoculture stands. Have studentsgive an oral report based on their findings.


Basic Concepts Transparency34 and Master

Basic Concepts Transparency35 and Master

Reinforcement and StudyGuide, p. 100

Content Mastery pp. 109,111-112 L1

P

LS

L2

P

LS

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS


Going FurtherGoing Further

Project Design a different key that wouldalso work to identify your specimens. Youmay expand your key to include additionalconifers.

To find out more aboutconifers, visit the Glencoe

Science Web Site. www.glencoe.com/sec/science

PLAN THE EXPERIMENTPLAN THE EXPERIMENT

1. Make a list of characteristicsthat could be included in yourkey. You might consider usingshape, color, size, habitat, orother factors.

2. Determine which of thosecharacteristics would be mosthelpful in classifying yourconifers.

3. Determine in what order thecharacteristics should appear inyour key.

4. Decide how to describe eachcharacteristic.

Check the Plan1. The traits described at each

fork in a key are often pairs of contrasting characteristics.For example, the first fork in a key to conifers might compare “needles grouped in bundles” with “needlesattached singly.”

2. Someone who is not familiarwith conifer identification


1. Checking Your Hypothesis Havesomeone outside your lab grouptry using your key to identifyyour conifer specimens. If theyare unable to make it work, try todetermine where the problem isand make improvements.

2. Making Inferences Is there onlyone correct way to design a keyfor your specimens? Explain whyor why not.

3. Relating Concepts Give one or more examples of situations

in which a key would be a useful tool.

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

should be able to use your keyto correctly identify anyconifer it includes.

3. Make sure your teacher hasapproved your experimentalplan before you proceed further.

4. Carry out your plan by creating your key.

Spruce

YOUR OWNDESIGN

YOUR OWNDESIGN

1. By using student key designon the overhead, the entireclass can determine whetheror not the key works.

2. Student key designs placedon the overhead will illustratethe diversity of student traitchoices used to organize anddesign each key.

3. It can distinguish poisonousfrom nonpoisonous plants,and harmful from nonharm-ful insects.

Error AnalysisMake sure students understandthat their keys must distinguishamong several similar conifers,each of which must be uniquelyidentified. Each fork in their keymust be specific and identifiable.

Performance Provide stu-dents with a bag of common labo-ratory items such as: glass slide,coverslip, paper clip, thumbtack,rubber band, staple, and dissect-ing needle. Ask them to prepare akey that identifies each item. Usethe Performance Task AssessmentList for Making and Using aClassification System in PASC,p. 49. L1

P

LS


ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

619

Data and ObservationsHave students record their keys and turnthem in at the end of class. Make trans-parencies of sample keys and use them inclass the following day as a means for illus-trating correct and incorrect key design.

Going FurtherGoing Further

Ask students to explain why akey design based on leaf odoror habitat may not be workableor practical.


How can you make a key foridentifying conifers?

YOUR OWNDESIGN

YOUR OWNDESIGN

ProblemWhat kinds of characteristics can

be used to create a key for identifyingdifferent kinds of conifers?

HypothesesState your hypothesis according to

the kinds of characteristics you thinkwill best serve to distinguish

among several conifergroups. Explain your

reasoning.

ObjectivesIn this BioLab, you will:■ Compare structures of several

different conifer specimens.■ Identify which characteristics can

be used to distinguish one coniferfrom another.

■ Communicate to others the distinguishing features of differentconifers.

Possible Materialstwigs, branches, and cones from several different conifers that havebeen identified for you

Safety PrecautionsAlways wash your hands after

handling biological materials. Alwayswear goggles in the lab.

Skill HandbookUse the Skill Handbook if you need

additional help with this lab.

PREPARATIONPREPARATION

M ost conifers have cones and needle- or scalelike leaves. Differentspecies have cones of different sizes, shapes, and thickness. The

leaves of different species also have different characteristics. How wouldyou go about identifying a conifer you are unfamiliar with? You wouldprobably use a biological identification key. Biological keys list features ofrelated organisms in a way that allows you to determine each organism’sscientific name. Below is an example of the selections that could be foundin a key that might be used to identify trees.

Needles grouped in bundles Needlelike leavesNeedles not grouped in bundles Flat, thin leavesLeaves composed of three or more leaflets Leaves not made up of leaflets

Pine needles

Hemlock

Arborvitae

YOUR OWNDESIGN

YOUR OWNDESIGN

618

Time AllotmentOne class period

Process Skillsobserve and infer, classify, com-pare and contrast, organize data

Safety PrecautionsSome of the needle and conespecimens are very sharp. Warnstudents of the possibility ofsticking themselves with thepointed ends.

Alternative Materials■ Specimens should contain both

leaves and cones. If unavailable,substitute scale diagrams of avariety of conifer leaf and conespecimens.

Possible Hypotheses■ The number of leaves per bun-

dle, length of leaves, shape ofleaves, color of leaves, andappearance of the sheath at thebase of the leaves are useful inclassifying conifers.

■ Cone shape, length, and diam-eter may be used to classifyconifers.

PREPARATIONPREPARATION

P

LS

PLAN THE EXPERIMENTPLAN THE EXPERIMENT

Teaching Strategies■ Label the samples with either their scien-tific names or generic labels such as ConiferA, Conifer B, etc. This will allow students toestablish whether or not a key actuallyworks when identification is attempted byanother group.■ Illustrate on the chalkboard or an over-head what an ideal key may look like. Point

out the nature of the opposite trait beingused at the fork.

Possible Procedures■ Student procedures will vary. However,

the general organization of the key itselfwill be similar from group to group.Making branches with opposite charac-teristics will help with the key design.


BioLab and MiniLab Work-sheets, pp. 103-104 L2

P

LS


Chapter 22 AssessmentChapter 22 Assessment

SUMMARYSUMMARY

Section 22.1

Section 22.2

Section 22.3

Main Ideas■ Nonvascular plants lack vascular tissue

and reproduce by producing spores. The gametophyte generation is dominant.

■ There are three divisions of nonvascular plants: Bryophyta,Hepatophyta, andAnthocerophyta.

Vocabularyarchegonium (p. 598)antheridium (p. 598)Nonvascular

Plants

Main Ideas■ The non-seed vascular plants were prominent

members of Earth’s ancient forests. They arerepresented by modern species.

■ Vascular tissues provide the structural supportthat enables vascular plants to grow taller thannonvascular plants.

■ There are three divisions of non-seed vascularplants: Lycophyta, Sphenophyta, andPterophyta.

Vocabularyprothallus (p. 602)rhizome (p. 605)sorus (p. 606)strobilus (p. 602)

Non-SeedVascular Plants

Seed Plants

CHAPTER 22 ASSESSMENT 621

Main Ideas■ There are four divisions of vascular plants that

produce naked seeds: Cycadophyta,Gnetophyta, Ginkgophyta, and Coniferophyta.

■ Seeds contain a supply of food to nourish theyoung plant, protect the embryo during harshconditions, and provide methods of dispersal.

■ Anthophytes produce flowers and have seedsenclosed in a fruit.

■ Anthophytes are either monocots or dicotsbased on the number of cotyledons present inthe seed.

■ Fruits provide protection for the seeds and aidin their dispersal.

■ Anthophytes may be annuals, biennials, orperennials.

Vocabularyannuals (p. 615)biennials (p. 616)cotyledon (p. 609)deciduous plant (p. 612)dicotyledons (p. 615)embryo (p. 608)fruit (p. 610)monocotyledons (p. 615)ovule (p. 608)perennials (p. 616)pollen grain (p. 608)

621

Main IdeasSummary statements can be used bystudents to review the major con-cepts of the chapter.

Using the VocabularyTo reinforce chapter vocabulary, usethe Content Mastery Booklet andthe activities in the Interactive Tutorfor Biology: The Dynamics of Life onthe Glencoe Science Web Site.www.glencoe.com/sec/science


All ChapterAssessment

questions and answers have beenvalidated for accuracy and suitabil-ity by The Princeton Review.

Hundreds of different kinds of trees grow intropical forests. But only a few are valuable

to the logging industry. Traditionally, loggers goafter only the most economically valuable tim-ber species, but in doing so they invade andclearcut millions of acres of forest each year.When loggers remove the economically valuabletrees, neighboring trees are often destroyed, andthe delicate ecology of the area is upset.

A “Sustainable” Harvest Many ecologists andconservation groups have worked to promote“sustainable” forestry as an alternative to tradi-tional logging. Sustainable forestry involves har-vesting a limited number of trees from specificareas of rain forest, and then nurturing youngtrees to replace those that are cut. The philoso-phy behind sustainable forestry is that it will cre-ate a constantly regenerating supply of valuabletimber and restrict logging to certain areas thatare carefully managed.

Different ViewpointsAlthough hundreds of millions of dollars

have been spent on sustainable forestry, only atiny fraction (less than 0.02 percent) of theworld’s tropical forests are managed sustainably.Logging companies make more money by log-ging forests the traditional way. Until loggingcompanies can make profits using sustainableforestry methods, there is little economic incen-tive for them to change their harvesting tech-niques.

More harm than good? Evidence suggests thatsustainable forestry may threaten biodiversitymore than traditional logging. Researchers havediscovered that the longer an area of forest is dis-turbed, the greater the threat to the plants andanimals that live there. With sustainable forestry,an area is disturbed for a long period of time.This may damage the biodiversity of a forest.

Still the best hope Sustainable forestry advo-cates maintain that although their alternativeisn’t perfect, it may still be the best way to pre-vent widespread damage to tropical forests byrestricting the damage that logging can do tosmaller, controlled areas.

Forestry: Keeping a BalanceTropical rain forests are Earth’s most biologically diverse ecosystems.Large areas of these forests are lost each year due to logging and theclearing of land for crops and cattle.

Analyzing the Issues Brainstorm in groups asto why some rain forest trees are more “valuable”than others. Discuss the link between thedemand for certain kinds of wood and rain forestdestruction. How might the demand be lessened?

To find out more about rain for-est destruction and sustainable

forestry, visit the Glencoe Science Web Site. www.glencoe.com/sec/science.

INVESTIGATING THE ISSUEINVESTIGATING THE ISSUE

620 Logged rain forest

620

PurposeStudents are exposed to the prosand cons of traditional rain forestlogging practices and sustainableharvesting alternatives.

BackgroundThe Amazon rain forest is shrink-ing by nearly 5 million acres peryear, losing an area the size ofseven football fields every minute.

Traditional logging practicesdamage the forest and threatenbiodiversity. In addition, loggingcompanies build roads throughforested areas. Farmers andranchers then use these roads togain access to new areas of forest.Trees and vegetation are burnedand the land cleared alongsidethe roads to make room for roadsand pastures.

Teaching Strategies■ Encourage students to do anInternet search for informationabout rain forest conservationprograms. Ask students to evalu-ate the feasibility of these pro-grams in protecting rain forestswhile satisfying the economicneeds of people living in theseregions.

Investigating the IssueIf consumers can be persuaded to use nontropical woods andbuilding materials, the demand for tropical timber would bereduced. This would reduce theneed for logging and decrease theamount of land lost to farmingand ranching.

P

LS

Going FurtherGoing FurtherGoing Further

Linguistic Have students write an es-say comparing the methods and re-

sults of sustainable harvest with traditionallogging. Have students propose alternativeforestry methods that might be better thaneither alternative. L3

P

LS

VIDEODISCThe Infinite Voyage: Life in the Balance

Rondonia: Home of a Dying Rain Forest(Ch. 3) 4 min.

!7ALD"

VIDEOTAPEMindJogger Videoquizzes

Chapter 22: The Diversity of Plants Have students work in groups as they playthe videoquiz game to review key chapterconcepts.


Chapter Assessment, pp. 127-132MindJogger VideoquizzesComputer Test BankBDOL Interactive CD-ROM, Chapter 22

quiz




CHAPTER 22 ASSESSMENT 623

ASSESSING KNOWLEDGE & SKILLSASSESSING KNOWLEDGE & SKILLS

The germination rate of seeds is the per-centage of planted seeds that eventuallysprout to produce new plants. The seeds ofthe bristlecone pine must be exposed to coldtemperatures before they will sprout.

Using a Graph Answer the following questions based on the graph.1. What would be the minimum time you

would keep bristlecone pine seeds underrefrigeration before planting?a. 1 month c. 6 monthsb. 3 months d. 80 months

2. How long does it take to get 50 percentgermination?a. 2-1/2 months c. 1 monthb. 6 months d. 80 months

3. Interpreting Scientific IllustrationsExamine the cross section of a coniferneedle as diagrammed in the Inside Storyand answer the following question. How do the positions of stomata andvascular tissues in the leaf help to prevent water loss?

Perc

ent o

f ger

min

atio

n

Months exposed to cold temperatures0

0

10%

50%

80%

1 2 3 4 5 6

Seed Germination Rate After Exposure to Cold

19. Because mosses lack vascular tissue, theamount of ________ in their environment isoften the limiting factor.

20. Plants that have a life span that lasts twoyears are called ________.

21. What is the adaptive advantage of fertilization that no longer requires a continuous film of water for the sperm to reach the eggs?

22. Why are conifers more abundant than flow-ering trees in Canada, Alaska, and Siberia?

23. Explain how evergreen and deciduous plants differ, and describe the adaptive value of each.

24. What might be the evolutionary advantagesof having a gametophyte dependent on asporophyte?

25. Comparing and Contrasting Compare andcontrast cones and fruits.

26. Observing and Inferring What traits couldyou use to identify anthophytes?

27. Concept Mapping Complete the conceptmap by using the following vocabulary terms:prothallus, archegonium, antheridium.

THINKING CRITICALLYTHINKING CRITICALLY

APPLYING MAIN IDEASAPPLYING MAIN IDEAS

1.

3.2.

For additional review, use the assessmentoptions for this chapter found on the Biology: TheDynamics of Life Interactive CD-ROM and on theGlencoe Science Web Site.www.glencoe.com/sec/science

CD-ROM

623

19. moisture/water20. biennials

21. Fertilization may occur at anytime because it is no longerdependent on water.

22. Conifer leaf adaptations allowthem to survive in cold, harshclimates.

23. Evergreens retain leaves all yearlong and can start to photosyn-thesize as soon as the growingseason starts. Deciduous plantslose their leaves, reducingwater loss during the winter.

24. The sporophyte protects thegametophyte and providesnourishment.

25. Cones and fruits both containseeds. However, the seeds incones are borne on scales whilethe seeds contained withinfruits are protected by the fruit.

26. Anthophytes have flowers andseeds contained within fruits.

27. 1. Prothallus; 2. Archegonium;3. Antheridium

THINKING CRITICALLYTHINKING CRITICALLY

APPLYING MAIN IDEASAPPLYING MAIN IDEAS


1. b2. a3. Sunken stomata and

internal vascular tissuehelp prevent water loss.


1. Bryophytes, hepatophytes, and anthocero-phytes are the three divisions of ________plants.a. vascular c. nonvascular b. seed d. evergreen

2. The ________ is the gametophyte of a lyco-phyte.a. sorus c. strobilusb. frond d. prothallus

3. Lycophytes include ________.a. ferns c. mossesb. conifers d. club mosses

4. Anthophytes and coniferophytes are divisionsthat are BOTH ________.a. vascular and seed-producingb. vascular and non-seedc. nonvascular and non-seedd. nonvascular and seed-producing

5. Vascular tissue is important because it helpsthe plant to ________.a. anchor into the soilb. reproducec. transport water and nutrientsd. photosynthesize

6. The plant in the photographis a(n) ________.a. Anthophytec. Sphenophyteb. Pterophyted. Gnetophyte

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS 7. About 280 million years ago, many of thenon-seed plants became extinct because of________.a. long periods of freezing and droughtb. a change to a warm, wet climatec. environmental pollution by humansd. being eaten by dinosaurs

8. The gametophyte generation is dominant inwhich of the following plants?a. pine trees c. apple treesb. ferns d. mosses

9. Which of the following is NOT a part of aseed?a. gametophyte c. food supplyb. protective coat d. embryo

10. An orange tree would be classified in thesame division as which of the following?a. pine tree c. cycadb. moss d. sunflower

11. The sporophyte structure shown here that protects the developingfemale gameto-phyte is the ________.

12. The thick, underground stem of a fern is the________.

13. Seed plants do not require a continuous filmof ________ to transport sperm to egg in fer-tilization

14. The moss sporophyte is dependent upon the________ for nutrition.

15. A ________ is a group of sporangia found ona fern leaf.

16. The stems of sphenophytes contain ________that gives them a rough texture.

17. Monocotyledons have only one seed leaf or________.

18. The presence of a single large ________ inthe cells of hornworts suggests they may beclosely related to algae.

622 CHAPTER 22 ASSESSMENT

TEST–TAKING TIPTEST–TAKING TIP

Cramming Is Not a Good StrategyIf you don’t know the material by the week beforethe test, you’re less likely to do well. Set up a timeline for your practice and preparation so thatyou’re not rushed; then you will have time to dealwith those problem areas.

622

1. c2. d3. d4. a5. c6. b7. a8. d9. a

10. d11. ovule12. rhizome13. water14. gametophyte15. sorus16. silica17. cotyledon18. chloroplast

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS



chapter 22: the diversity of plants · 596 the diversity of plants the diversity of plants what...

Documents