Chapter 21Chapter 21

TheThePlant KingdomPlant Kingdom

Chapter 21 2

PlantsPlants

Plants and peoplePlants and people

Plants, medicines, and bioprospectingPlants, medicines, and bioprospecting

The roles of plants in the ecosystemThe roles of plants in the ecosystem

The evolutionary origin of plantsThe evolutionary origin of plants• Division Rhodophyta—red algaeDivision Rhodophyta—red algae

• Division Phaeophyta—brown algaeDivision Phaeophyta—brown algae

• Division Chlorophyta—green algae and the Division Chlorophyta—green algae and the origin of land plantsorigin of land plants

Chapter 21 3

HaploidHaploidDiploidDiploid

GametophytesGametophytesform by meiosisform by meiosis

Spores formSpores formby meiosisby meiosis

nnnnnn

Alternation of GenerationsAlternation of Generationsin Plantsin Plants

SporeSporeMotherMother

CellCell

EggEgg

SpermSpermGametes meetGametes meet& fuse to form& fuse to formzygotezygote

ZygoteZygote

EmbryoEmbryoSporo-Sporo-phytephyte

22nn

SporesSporesnn

Gameto-Gameto-phytephyte

22nn

nnnn

22nn

22nn

22nn

Chapter 21 4

The Evolution of Land PlantsThe Evolution of Land PlantsRoots and rootlike structuresRoots and rootlike structuresVascular tissue for transport of water & nutrientsVascular tissue for transport of water & nutrientsStiffening substance (lignin) for supportStiffening substance (lignin) for supportWaxy covering (cuticle) limits evaporationWaxy covering (cuticle) limits evaporationStomatal poresStomatal pores• Mediate gas exchangeMediate gas exchange• Regulate water vapor lossRegulate water vapor loss

Evolutionary adaptations in plant reproductionEvolutionary adaptations in plant reproduction• Early algae relied on water currents for fertilizationEarly algae relied on water currents for fertilization• Dry land adaptation include the generation of Dry land adaptation include the generation of

pollen, seeds, flowers, and fruitpollen, seeds, flowers, and fruit• Adaptations in the alternation of generationsAdaptations in the alternation of generations

Chapter 21 5

Evolutionary Evolutionary TreeTreeof Major of Major Plant Plant GroupsGroups

AncestralAncestralAlgaeAlgae

AncestralAncestralAlgaeAlgae

Liver-Liver-wortsworts MossesMosses

BryophytesBryophytes

True vascular tissueTrue vascular tissue& lignin appear& lignin appear

FernsFerns Gymno-Gymno-spermssperms

Seeds andSeeds andpollen appearpollen appear

Flowers &Flowers &Fruits appearFruits appear

Seed PlantsSeed Plants

Angio-Angio-spermssperms

TracheophytesTracheophytes

Chapter 21 6

The BryophytesThe Bryophytes

Nonvascular plantsNonvascular plants

No true roots, leaves, and stemsNo true roots, leaves, and stems

Still require a moist environmentStill require a moist environment

Anchoring rhizoids absorb water & nutrientsAnchoring rhizoids absorb water & nutrients

Reproductive structures protect gametesReproductive structures protect gametes

Still depend on water for fertilizationStill depend on water for fertilization

Dominant gametophyte generationDominant gametophyte generation

Chapter 21 7

Life Life Cycle Cycle

of a of a Moss Moss

(a)(a)

Zygote develops intoZygote develops intosporophyte withinsporophyte withingametophytegametophyte

SporophyteSporophyteCapsule Capsule

Fertilization Fertilization

Mei

osis

M

eios

is

Haploid spores liberatedHaploid spores liberatedfrom sporophyte capsulefrom sporophyte capsule

OldOldGametophyteGametophyte

Spores disperseSpores disperseand germinateand germinate

HaploidHaploid11nn

DiploidDiploid22nn

Chapter 21 8

Life Life Cycle Cycle

of a of a Moss Moss

(b)(b)HaploidHaploid

11nn

DiploidDiploid22nn

Spore germinatesSpore germinatesinto gametophyteinto gametophyte

LeafyLeafyGametophyteGametophyte

ArchegoniumArchegoniumproduces eggproduces egg

AntheridiumAntheridiumproduces spermproduces sperm

Sperm swimSperm swimto eggto egg

FertilizationFertilization

Chapter 21 9

Liverworts & MossesLiverworts & MossesLiverwortsLiverwortsFemaleFemale

GametophyteGametophyteArchegoniumArchegonium

(a)(a)(a)(a) (b)(b)(b)(b)

MossesMosses

FemaleFemaleGametophytesGametophytes

SporophytesSporophytes

Chapter 21 10

Division Tracheophyta:Division Tracheophyta:Vascular PlantsVascular Plants

Adapted to life in drier conditionsAdapted to life in drier conditions• Had to generate body supportHad to generate body support

• Vessels to conduct water and nutrientsVessels to conduct water and nutrients

• A stiffening substance called ligninA stiffening substance called lignin

Seedless plants: club mosses, horsetails, Seedless plants: club mosses, horsetails, and fernsand ferns• Sporophyte generation more dominantSporophyte generation more dominant

• Fertilization still relies on waterFertilization still relies on water

Chapter 21 11

Life Cycle Life Cycle of Ferns (a)of Ferns (a)

HaploidHaploid11nn

DiploidDiploid22nn

GametophyteGametophyte

Sporophyte developsSporophyte developsfrom gametophytefrom gametophyte

RootRoot

StemStem

SporophyteSporophyte

Masses ofMasses ofSporangiaSporangia

MeiosisMeiosis

Haploid spores liberatedHaploid spores liberatedfrom sporangiumfrom sporangium

SporangiumSporangium

Chapter 21 12

Life Cycle of Ferns (b)Life Cycle of Ferns (b)

HaploidHaploid11nn

DiploidDiploid22nn

Haploid spores liberatedHaploid spores liberatedfrom sporangiumfrom sporangium

Spores disperseSpores disperse& germinate& germinate

GametophyteGametophyte

ArchegoniumArchegoniumproduces eggproduces egg

AntheridiumAntheridiumproduces spermproduces sperm

Sperm swimSperm swimto eggto egg

FertilizationFertilization

Chapter 21 13

Seed Plants:Seed Plants:GeneralGeneral

Dominance of the sporophyte generationDominance of the sporophyte generation

Reproductive adaptationsReproductive adaptations• Pollen Pollen

– Wind and pollinators for fertilizationWind and pollinators for fertilization– Water not required for fertilizationWater not required for fertilization

• SeedsSeeds– Stores food for embryoStores food for embryo– Embryo protection for unfavorable environmentsEmbryo protection for unfavorable environments

Chapter 21 14

SeedsSeeds

(a) Gymnosperm(a) Gymnosperm (d) Water Dispersal(d) Water Dispersal

(c) Wind Dispersal(c) Wind Dispersal

Stored FoodStored FoodStored FoodStored Food

EmbryoEmbryoEmbryoEmbryo

Seed CoatSeed CoatSeed CoatSeed Coat (b) Angiosperm(b) Angiosperm

Chapter 21 15

Seed Plants:Seed Plants:GymnospermsGymnosperms

Nonflowering seed plantsNonflowering seed plantsProduce "naked seeds"Produce "naked seeds"Three divisions:Three divisions:• ConiferophytaConiferophyta• CycadophytaCycadophyta• GinkgophytaGinkgophyta

Conifers are adapted to dry, cold conditionsConifers are adapted to dry, cold conditions• Thin, waterproof needles to decrease evaporationThin, waterproof needles to decrease evaporation• Evergreen; year-round photosynthesisEvergreen; year-round photosynthesis• Produce an "antifreeze" substance in sapProduce an "antifreeze" substance in sap

Chapter 21 16

Two UncommonTwo UncommonGymnospermsGymnosperms

(a) Gingko(a) Gingko

(b) A Cycad(b) A Cycad

Chapter 21 17

Life Life Cycle of Cycle of the Pine the Pine (a) (a)

HaploidHaploid11nn

DiploidDiploid22nn

MatureMatureSporophyteSporophyte

MatureMatureSporophyteSporophyte

SeedlingsSeedlings(Sporophyte)(Sporophyte)SeedlingsSeedlings

(Sporophyte)(Sporophyte)

MaleMaleConeConeMaleMale

ConeCone

MaleMaleScaleScale

MaleMaleScaleScale

MEIOSISMEIOSIS

MEIOSISMEIOSIS

Male gametophytesMale gametophytes(pollen) liberated(pollen) liberated

FemaleFemaleConeCone

FemaleFemaleConeCone

FemaleFemaleScaleScale

FemaleFemaleScaleScale

OvuleOvuleOvuleOvule

Spore-formingSpore-formingCellCell

Spore-formingSpore-formingCellCell

MEIOSISMEIOSIS

MEIOSISMEIOSIS

Chapter 21 18

Life Cycle of the Pine (b)Life Cycle of the Pine (b)

HaploidHaploid11nn

DiploidDiploid22nn

MEIOSISMEIOSIS

MEIOSISMEIOSIS

Pollen liberated;Pollen liberated;Dispersed by windDispersed by wind

MEIOSISMEIOSIS

MEIOSISMEIOSIS

SeedlingsSeedlings(Sporophyte)(Sporophyte)SeedlingsSeedlings

(Sporophyte)(Sporophyte)

Egg CellEgg CellEgg CellEgg Cell

FemaleFemaleGametophyteGametophyte

FemaleFemaleGametophyteGametophyte

Pollen lands onPollen lands onfemale scalefemale scale

PollenPollenTubeTube

PollenPollenTubeTube

FERTILIZATIONFERTILIZATIONFERTILIZATIONFERTILIZATION

SeedSeedSeedSeed

EmbryoEmbryoEmbryoEmbryo

Chapter 21 19

Seed Plants:Seed Plants:AngiospermsAngiosperms

Flowering seed plantsFlowering seed plantsThe dominant plant form on EarthThe dominant plant form on EarthMajor evolutionary adaptationsMajor evolutionary adaptations• Flowers to attract pollinatorsFlowers to attract pollinators• Fruit to protect seeds and developing embryoFruit to protect seeds and developing embryo• Broad leavesBroad leaves

– Increase photosynthesis during the growing seasonIncrease photosynthesis during the growing season– Shed during periods of cold and droughtShed during periods of cold and drought

Class Monocotyledoneae (monocots): grasses, Class Monocotyledoneae (monocots): grasses, grains, corngrains, corn

Class Dicotyledoneae (dicots): hardwood trees, Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbsshrubs, and herbs

Chapter 21 20

Life Cycle of aLife Cycle of aFlowering Plant (a)Flowering Plant (a)

FruitFruitFruitFruit

SeedSeedSeedSeed

FoodFoodFoodFoodEmbryoEmbryoEmbryoEmbryo

Seed CoatSeed CoatSeed CoatSeed Coat

SeedlingSeedlingSeedlingSeedling FlowerFlowerFlowerFlowerAntherAntherAntherAnther

MEIOSISMEIOSISMEIOSISMEIOSIS

OvaryOvaryOvaryOvary

OvuleOvuleOvuleOvule

Spore-formingSpore-formingCellCell

Spore-formingSpore-formingCellCell

HaploidHaploid11nn

DiploidDiploid22nn

Chapter 21 21

Life Cycle of a Flowering Plant (b)Life Cycle of a Flowering Plant (b)

FruitFruitFruitFruit

MEIOSISMEIOSISMEIOSISMEIOSIS

MEIOSISMEIOSIS

MEIOSISMEIOSIS

SporeSporeSporeSpore

FemaleFemaleGametophyteGametophyte

FemaleFemaleGametophyteGametophyte

Egg CellEgg CellEgg CellEgg Cell

Pollen (malePollen (malegametophyte)gametophyte)Pollen (malePollen (male

gametophyte)gametophyte)

StigmaStigmaStigmaStigma

PollenPollenTubeTube

PollenPollenTubeTube

SpermSpermNucleiNuclei

SpermSpermNucleiNuclei

FERTILIZATION

FERTILIZATION

FERTILIZATION

FERTILIZATION

HaploidHaploid11nn

DiploidDiploid22nn

Chapter 21Chapter 21

The EndThe End