植物学教案-根形态.ppt

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1、Chapter4PlantOrgansDefinition:Adistinctstructurecomposedofavarietyoftissues.Vegetativeorgans:Absorption,productionandprovisionofnutrients.roots,stemsandleaves.Reproductiveorgans:productionofnextgeneration.flowers,fruitsandseeds.Section1TheRootFunctionsandCharacteristicsFormsand

2、ModificationsPrimaryandSecondaryStructuresFunctionsAnchorageStorageAbsorptionProductionCharacteristicsGeotropismHydrotropismNegativephototropismFormsNormalroot:originatesdirectly(mainroot)orindirectly(lateralroot)fromtheembryonicroot(radicle).Adventitiousroot:originatesfrompare

3、nchymaofstemsorleaves(fibrousroot).TheRootSystemsTaprootsystem:Alargetaprootandsmallerbranchroots.Occuringymnospermsanddicots.Fibrousrootsystem:theradicleisshort-livedandisreplacedbyamassofadventitiousroots.Occurinmostmonocots.TheRootModificationsStorageroots:fleshytaprootsandr

4、oottubers.ProprootsClimbingrootsAerialrootsParasiticrootsMycorrhizalrootsAirrootsNodulesTheInternalStructuresTheRootTip:RootcapRegionofdivisionRegionofelongationRegionofmaturationThePrimaryStructureTheSecondaryStructureTheRootTipRootCapFeatures:acap-likestructurecomposedofparen

5、chymacellswithamyloplasts.Functions:ProtectingtheapicalmeristemAidingtheroot’spenetrationInvolvedingeotropism.TheRootTipRegionofCellDivisionFeatures:Composedoftheapicalmeristemanditsderivatives.Celldivisionoccurs.Functions:Increasecellnumbersandcelllayersbycelldivision.Producet

6、heprimarymeristemTheRootTipRegionofElongationFeatures:Composedofgrowingcells,elongatinganddifferentiating.Functions:resultsinmostoftheincreaseinlengthoftheroot,producingprimarystructures.TheRootTipRegionofMaturationFeatures:Mostcellsoftheprimarytissuesmature,roothairsbeingprodu

7、ced.Functions:Themainregionofabsorption.