The Plant Kingdom: Seed Plants Chapter 28. Learning Objective 1 Compare the features of gymnosperms...

The Plant Kingdom:The Plant Kingdom:Seed PlantsSeed Plants

Chapter 28 Chapter 28

Learning Objective 1Learning Objective 1

• Compare the features of Compare the features of gymnospermsgymnosperms and and angiospermsangiosperms

Two Groups of Seed PlantsTwo Groups of Seed Plants

• GymnospermsGymnosperms • seeds are totally exposed or borne on the seeds are totally exposed or borne on the

scales of conescales of cone• ovary wall does not surround the ovulesovary wall does not surround the ovules

• AngiospermsAngiosperms • flowering plants flowering plants • produce seeds within a fruit (a mature ovary)produce seeds within a fruit (a mature ovary)

Gymnosperm and Angiosperm Gymnosperm and Angiosperm EvolutionEvolution

Fig. 28-2, p. 602

Gymnosperms

Cyc

ads

Gin

kgo

es

Co

nif

ers

Gn

eto

ph

ytes

An

gio

sper

ms

Evolution of flowering plants

Evolution of seeds

KEY CONCEPTSKEY CONCEPTS

• Seed plants include gymnosperms and Seed plants include gymnosperms and angiospermsangiosperms


• Trace the steps in the life cycle of a pineTrace the steps in the life cycle of a pine

• Compare its sporophyte and gametophyte Compare its sporophyte and gametophyte generationsgenerations

ConifersConifers

Fig. 28-3 (1), p. 603

Gymnosperms

Cyc

ads

Gin

kgo

es

Co

nif

ers

Gn

eto

ph

ytes

An

gio

sper

ms

Fig. 28-3 (a-c), p. 603

Pine Life Cycle 1Pine Life Cycle 1

• Pine treePine tree• a mature sporophytea mature sporophyte

• Pine gametophytesPine gametophytes• extremely smallextremely small• nutritionally dependent on sporophyte nutritionally dependent on sporophyte

generation generation


• Pine is heterosporousPine is heterosporous• produces microspores and megaspores in produces microspores and megaspores in

separate conesseparate cones

• Male cones produce Male cones produce microsporesmicrospores that that develop into develop into pollen grainspollen grains (immature male (immature male gametophytes) gametophytes) • carried by air currents to female conescarried by air currents to female cones


• Female cones produce Female cones produce megasporesmegaspores

• One of each four megaspores (meiosis) One of each four megaspores (meiosis) develops into a female gametophytedevelops into a female gametophyte• within an within an ovule (megasporangium)ovule (megasporangium)


• PollinationPollination• transfer of pollen to female conestransfer of pollen to female cones

• Pollen tubePollen tube• grows through megasporangium to egg within grows through megasporangium to egg within

archegoniumarchegonium

• After After fertilizationfertilization• zygote develops into embryo encased inside zygote develops into embryo encased inside

seed adapted for wind dispersalseed adapted for wind dispersal

Pine Life CyclePine Life Cycle

Fig. 28-4, p. 604

Each scale bears two microsporangiaMicrosporangium2

Microspores, each of which develops into a pollen grain

Pollen grains are transferred to the female cone by wind 3

Scale from a male coneMale

cone 4Scale from a female cone Female

gametophyte

Each scale bears two ovules (megasporangia)

Megasporangium

Megaspore Growing pollen tubeOvule

HAPLOID (n) GAMETOPHYTE GENERATIONMeiosis FertilizationImmature

female cone

DIPLOID (2n) SPOROPHYTE GENERATION

5Zygote

Second sperm nucleus

Papery wings

Pollen tube Sperm nucleus united with egg nucleus

Seed coat

Male cones (pollen cones) 1

6

Embryo Two seeds on the upper surface of the scale

Mature female cone (seed cone)

Newly germinated seedling

Female gametophyte (nutritive tissue)Pine (mature sporophyte)

3

Insert “Pine life cycle”Insert “Pine life cycle”

pine_life_cycle.swfpine_life_cycle.swf


• What features distinguish What features distinguish gymnospermsgymnosperms from from bryophytesbryophytes and and fernsferns??

GymnospermsGymnosperms

• Are vascular plants Are vascular plants • unlike bryophytesunlike bryophytes

• Produce seeds Produce seeds • unlike bryophytes and fernsunlike bryophytes and ferns

• Produce wind-borne pollen grainsProduce wind-borne pollen grains• unlike ferns and other seedless vascular unlike ferns and other seedless vascular

plants plants


• Gymnosperms produce exposed seeds, Gymnosperms produce exposed seeds, usually in cones borne on the sporophytesusually in cones borne on the sporophytes


• What are the four phyla of What are the four phyla of gymnospermsgymnosperms??

ConifersConifers (Phylum Coniferophyta)(Phylum Coniferophyta)

• Largest phylum of gymnospermsLargest phylum of gymnosperms

• Woody plants that bear Woody plants that bear needlesneedles (leaves (leaves that are usually evergreen)that are usually evergreen)• produce seeds in cones produce seeds in cones

• Most are Most are monoeciousmonoecious • have male and female reproductive parts in have male and female reproductive parts in

separate cones on same plantseparate cones on same plant

Male and Female ConesMale and Female Cones


• Conifers are the most diverse and Conifers are the most diverse and numerous of the four living gymnosperm numerous of the four living gymnosperm phylaphyla

CycadsCycads (Phylum Cycadophyta)(Phylum Cycadophyta)

• Palmlike or fernlike in appearance Palmlike or fernlike in appearance

• Are Are dioeciousdioecious• have male and female reproductive structures have male and female reproductive structures

on separate plantson separate plants• but reproduce with pollen and seeds in but reproduce with pollen and seeds in

conelike structuresconelike structures

CycadsCycads

Fig. 28-6 (1), p. 605

Gymnosperms

Cyc

ads

Gin

kgo

es

Co

nif

ers

Gn

eto

ph

ytes

An

gio

sper

ms

Fig. 28-6a, p. 605

Female strobilus (seed cone)

Fig. 28-6b, p. 605

Phylum GinkgophytaPhylum Ginkgophyta

• Ginkgo bilobaGinkgo biloba• only surviving species in phylumonly surviving species in phylum• deciduous, dioecious treedeciduous, dioecious tree

• Female Female ginkgoginkgo produces fleshy seeds produces fleshy seeds directly on branchesdirectly on branches

GinkgoGinkgo

Fig. 28-7 (1), p. 606

Gymnosperms

Cyc

ads

Gin

kgo

es

Co

nif

ers

Gn

eto

ph

ytes

An

gio

sper

ms

Fig. 28-7a, p. 606

Fig. 28-7b, p. 606

GnetophytesGnetophytes (Phylum Gnetophyta)(Phylum Gnetophyta)

• Share some traits with angiospermsShare some traits with angiosperms

Fig. 28-8 (1), p. 607

Gymnosperms

Cyc

ads

Gin

kgo

es

Co

nif

ers

Gn

eto

ph

ytes

An

gio

sper

ms

GnetophytesGnetophytes


• What features distinguish What features distinguish flowering plantsflowering plants from other plants?from other plants?

Flowering PlantsFlowering Plants

• Angiosperms (phylum Anthophyta)Angiosperms (phylum Anthophyta)

• Vascular plants that produce flowers and Vascular plants that produce flowers and seeds enclosed within a seeds enclosed within a fruitfruit

• Most diverse and successful plant groupMost diverse and successful plant group


• FlowerFlower• sepals, petals, stamens,sepals, petals, stamens, carpelscarpels• functions in sexual reproductionfunctions in sexual reproduction

• Ovules enclosed within Ovules enclosed within ovaryovary• unlike gymnospermsunlike gymnosperms

• After fertilizationAfter fertilization• ovules become seedsovules become seeds• ovary develops into fruitovary develops into fruit

Floral Floral StructureStructure

Fig. 28-10a, p. 609

Fig. 28-10b, p. 609

Female floral parts Male floral parts

Pollen grain (each will produce two sperm cells)

Stigma

StylePISTIL (consisting of one or more carpels)

AntherSTAMEN

Ovary FilamentOvules (each producing one egg cell)

Petal

SepalReceptacle

Peduncle

Parts of a FlowerParts of a Flower

Fig. 28-11a, p. 610

Petals Sepals

Fig. 28-11b, p. 610

Stamen

Pistil

Simple and Simple and Compound Compound

PistilsPistils

Fig. 28-12a, p. 611

Stigma

Ovules

Style

OvaryOvary wall

Fig. 28-12b, p. 611

One carpelOvules

Stigma

Style

Ovary wall

Ovary

Fig. 28-12b, p. 611

Ovary

Stigma

Style

One carpel

Ovary wall

Ovules

Stepped Art


• Angiosperms produce ovules enclosed Angiosperms produce ovules enclosed within carpels; following fertilization, seeds within carpels; following fertilization, seeds develop from the ovules, and the ovaries develop from the ovules, and the ovaries of carpels become fruitsof carpels become fruits


• Explain the life cycle of a Explain the life cycle of a flowering plantflowering plant

• Describe Describe double fertilizationdouble fertilization

Flowering Plant Life Cycle 1Flowering Plant Life Cycle 1

• Sporophyte generation dominantSporophyte generation dominant

• Gametophytes extremely reduced in sizeGametophytes extremely reduced in size• nutritionally dependent on sporophyte nutritionally dependent on sporophyte

generation generation

• HeterosporousHeterosporous• produce microspores, megaspores in flowerproduce microspores, megaspores in flower


• MicrosporeMicrospore develops into a pollen grain develops into a pollen grain (immature male gametophyte) (immature male gametophyte)

• One of each four One of each four megasporesmegaspores (meiosis) (meiosis) develops into develops into embryo sacembryo sac (female (female gametophyte) gametophyte)


• Embryo sac contains seven cells with Embryo sac contains seven cells with eight nucleieight nuclei

• Egg cell and central cell with two Egg cell and central cell with two polar polar nucleinuclei participate in fertilization participate in fertilization

Flowering Plant Life CycleFlowering Plant Life Cycle

Fig. 28-13, p. 612

Developing pollen tube of mature male gametophyte

Pollination6Each microspore

develops into a pollen grain

Embryo sac (mature female gametophyte)5 Pollen grain

(immature male

gametophyte)

MicrosporeTetrad of microspores Pollen

tube3

Polar nucleiMegaspore Two sperm

cellsEgg nucleus

HAPLOID (n) GAMETOPHYTE GENERATION

Meiosis Double fertilizationDIPLOID (2n)

SPOROPHYTE GENERATION

74 2

MegasporocyteEndosperm (3n)

Ovary

Zygote (2n)

Fruit

8

EmbryoSeed

Microsporocytes within microsporangia

Seed coat

SeedlingAnther 1Flower of mature sporophyte

Megasporangium (ovule)

Double FertilizationDouble Fertilization

• Characteristic of flowering plantsCharacteristic of flowering plants

• Results in formation ofResults in formation of• diploid zygotediploid zygote• triploid triploid endospermendosperm

Insert “Monocot life Insert “Monocot life cycle”cycle”

angiosperm_cycle.swfangiosperm_cycle.swf

Explore plant life cycles by Explore plant life cycles by clicking on the figures in clicking on the figures in

ThomsonNOW.ThomsonNOW.


• Contrast Contrast eudicotseudicots and and monocotsmonocots, the two , the two largest classes of flowering plantslargest classes of flowering plants

MonocotsMonocots (Class Monocotyledones)(Class Monocotyledones)

• Most have floral parts in threesMost have floral parts in threes

• Seeds each contain Seeds each contain 11 cotyledoncotyledon

• EndospermEndosperm • nutritive tissue in mature seedsnutritive tissue in mature seeds

Eudicots (Class Eudicotyledones)Eudicots (Class Eudicotyledones)

• Usually have floral parts in fours or fivesUsually have floral parts in fours or fives• or multiples thereofor multiples thereof

• Seeds each contain Seeds each contain 2 cotyledons2 cotyledons

• Cotyledons Cotyledons • nutritive organs in mature seedsnutritive organs in mature seeds• absorbed nutrients in endospermabsorbed nutrients in endosperm

Monocot and EudicotMonocot and Eudicot


• What are the evolutionary adaptations of What are the evolutionary adaptations of flowering plants?flowering plants?

ReproductionReproduction

• Flowering plants reproduce sexually by Flowering plants reproduce sexually by forming forming flowersflowers

• After After double fertilizationdouble fertilization, seeds form within , seeds form within fruitsfruits

• Wind, water, insects, animals transfer Wind, water, insects, animals transfer pollen grainspollen grains

StructuresStructures

• Efficient water-conducting Efficient water-conducting vessel elementsvessel elements in in xylemxylem

• Efficient carbohydrate-conducting Efficient carbohydrate-conducting sieve sieve tube elementstube elements in in phloem phloem


• Angiosperms, which compose a single Angiosperms, which compose a single phylum, dominate the land and exhibit phylum, dominate the land and exhibit great diversity in both vegetative and great diversity in both vegetative and reproductive structuresreproductive structures

Insert “Flower parts”Insert “Flower parts”

flower_parts.swfflower_parts.swf

Learn more about flower Learn more about flower structure by clicking on the structure by clicking on the

figure in ThomsonNOW.figure in ThomsonNOW.


• Summarize the evolution of gymnosperms Summarize the evolution of gymnosperms from seedless vascular plantsfrom seedless vascular plants

• Trace the evolution of flowering plants Trace the evolution of flowering plants from gymnospermsfrom gymnosperms

Evolution 1Evolution 1

• Seed plantsSeed plants arose from arose from seedless vascular seedless vascular plantsplants

• ProgymnospermsProgymnosperms• seedless vascular plantsseedless vascular plants• had megaphylls and “modern” woody tissuehad megaphylls and “modern” woody tissue• probably gave rise to probably gave rise to conifersconifers and and seed fernsseed ferns

• ProgymnospermProgymnosperm

• Seed FernSeed Fern


• Seed fernsSeed ferns• probably gave rise to cycads and ginkgoprobably gave rise to cycads and ginkgo

• Evolution of Evolution of gnetophytesgnetophytes, particularly their , particularly their relationship to flowering plants, is unclearrelationship to flowering plants, is unclear


• Flowering plantsFlowering plants probably descended from probably descended from gymnosperms with specialized featuresgymnosperms with specialized features• leaves with broad, expanded bladesleaves with broad, expanded blades• closed carpels closed carpels

• Flowering plantsFlowering plants likely arose only once likely arose only once

Fossil AngiospermsFossil Angiosperms

Fig. 28-17, p. 615

Carpel

Ovule

5 mm

Fig. 28-18, p. 615

Pistils

Scars on reproductive axis

7 mm

Evolution of Flowering PlantsEvolution of Flowering Plants

Fig. 28-19a, p. 616

Basal Angiosperms Core Angiosperms

Am

bo

rell

a

Wat

er l

ilie

s

Sta

r an

ise

Mag

no

liid

s

Mo

no

cots

Eu

dic

ots

Evolution of vessel elements

Evolution of flowering plants

Fig. 28-19b, p. 616

Fig. 28-19c, p. 616

Fig. 28-19d, p. 616

Fig. 28-19e, p. 616


• Gymnosperms and angiosperms evolved Gymnosperms and angiosperms evolved from ancestral seedless vascular plantsfrom ancestral seedless vascular plants

The Plant Kingdom: Seed Plants Chapter 28. Learning Objective 1 Compare the features of gymnosperms...

Documents

Transcript of The Plant Kingdom: Seed Plants Chapter 28. Learning Objective 1 Compare the features of gymnosperms...