Plant Reproduction Why reproduce? - PowerPoint Presentation

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Plant Reproduction

Why reproduce?Sexual vs. asexual reproductionSexual reproduction in plantsGametophytes and sporophytesGymnosperms and angiospermsAsexual reproduction in plantsAsexual reproduction using fragmentsAsexual reproduction using special structuresSlide2

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Plants Must Reproduce

Makes more plantsEnsures the continuation of the speciesPlants can reproduce _________Slide4

Sexual Reproduction in Plants

Usually needs pollinators (e.g. bees, birds, butterflies).Flowers attract insects, birds, and other animals._________Some self-pollinate, while others cannot._________Slide5

Asexual Reproduction in Plants

_________Does not involve joining of cells.Creates new plants identical to parent plant.Slide6

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Sexual Reproduction in PlantsGametes

are created by meiosisMeiosis: _________Gametes produced in special structures called gametangia………………Male gametangia: antheridiaSlide8

Sexual Reproduction in PlantsPlants can be bisexual or unisexual

Bisexual (monoecious): ___________Unisexual (dioecious): ____________Bisexual plants can’t always self-fertilizeSometimes incompatibleCross-fertilization preferredSlide9

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Sporophyte

Diploid individual

Sporocytes

(fertile cells) produce haploid spores via meiosis

_________Slide11

Sexual Reproduction in PlantsLiverworts and hornworts

……………….……………….Sperm release and fertilization require moisture (heavy dew or rain)_____________

Spores may germinate immediately upon deposition or undergo a period of dormancy first

Liverwort with sporophytes growing from archegoniaSlide12

Sexual Reproduction in PlantsLiverworts and HornwortsSlide13

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Sexual Reproduction in PlantsSpore plants

Includes seed plants and cryptogams (no flowers or seeds)Sporophyte stage dominantSeed plants_______________CryptogamsSpores shed from plant after producing gametophyte_______________Slide16

Sexual Reproduction in PlantsThere are two groups of seed

plantsGymnospermsAngiospermsThere are two types of sporesMegaspores: large spores; _______________Microspores: small spores; ______________Male gametophytes called pollen grainsSlide17

Gymnosperms and AngiospermsProduce seeds

______________Passageway through layers on megasporangiumOvule matures as seedOne megasporocyte ____________……………..………………Microspores develop inside microsporangiaPollen grains develop tube to pass sperm to egg____________Slide18

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GymnospermsCycads

____________Pollen grains shed from microsporangia………………..Ovule produces pollination dropletWind-borne pollen grains attach to dropletDroplet pulled back into ovule____________Slide21

GymnospermsPines

____________Sporophyte may become a large treePollen has air-filled wings between layers of pollen grain wall____________Scales on female gametophyte separate and pollen sticks to pollination dropletDroplet ……………..Fertilization occurs around 14 months after pollinationSlide22

Angiosperms

____________

Seeds

enclosed during development in structure called pistil or carpel

____________

Gametophytes

don’t have archegonia

Pollen transferred to surface of megaspore

____________

One

joins egg and

forms the zygote

Other joins two nuclei of female gametophyte to form storage tissue that serves as food source for embryo

After fertilization, ovule increases to mature seed sizeSlide23

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Angiosperms

Some monoecious species

Corn

Hickory

Walnut

Pecan

Oak

Some

……………Slide27

Angiosperms

Microspores develop pollen grains (male gametophytes)

Forms generative cell and tube cell

_____________

Pollination: transfer of pollen grains from anther of stamen to stigma of pistil

Some flowers can self-pollinate (e.g. peas and tomatoes)

Others need pollinators (e.g. insects) to transfer pollen between flowersSlide28

Angiosperms

One

megasporocyte

……………

.

.

___________

Only one enlarges, others degenerate

Enlarged

cell divides into seven (with eight nuclei)

___________

Three nuclei move to end opposite

micropyle

(opening where pollen tube enters) and become antipodal cells, which degenerate

__________

Last two nuclei help guide pollen tube, then disintegrateSlide29

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Angiosperms

Pollen passes down

the pollen

tube, through micropyle, and into gametophyte

One sperm fertilizes egg nucleus

Other unites with two nuclei in large central cell

___________

Endosperm nucleus

Divides into endosperm tissue

__________Slide31

Angiosperms

Ovary, ovules, and zygote grow

Embryo develops

Seed:

__________

Seeds become dormant and form hard seed coats

____________

Seeds

……………

.

.

Cotyledons

can help digest and absorb endosperm, be food sources themselves, or become photosynthetic leaves above the soil surfaceSlide32

AngiospermsSlide33

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Asexual Reproduction in Plants

Two basic types________________________Slide35

Asexual Reproduction Using FragmentsThe body of the plant fragments.

Pieces fall off.__________Fragmenting PlantsFernsLiverwortsMossesSucculentsWillows and poplarsSlide36

Asexual Reproduction Using Fragments

Piece of stem or roots from some plants can be cut off and planted. ___________Slide37

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Asexual Reproduction Using Special Structures

___________No union of sex cellsIn flowering plants, organs include:RhizomesTubers StolonsCorms BulbsSlide40

Rhizomes

Long, fleshy,

……………

..

Branch to grow new plants

__________Slide41

Tubers

Enlarged tips of underground rhizomes or

stolons

__________

Potatoes are tubersEyes are buds and can grow into new individualsSlide42

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Corms

Vertical, fleshy, underground stems

__________

Secondary

cormlets can grow into new baby plantsGladioli have cormsSlide44

Bulbs

Small bit of stem tissue ………………Undergo period of dormancyGrow into new plants____________Onions form bulbs