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PlantTissue—Dermaland VascularTissue Botany1 Mrs.Russell Objec=ves • Knowthemeristemspresentinplantsand wheretheyarefound • Learntheconduc=ng=ssueinplantsandthe func=onofeachcellcomponent • Knowthethree=ssuesystemsinplants TissueSystems • DermalTissue(theskin) – Epidermis • VascularTissue(thebloodstream) – Xylem – Phloem • GroundTissue(everythingelse) – Parenchyma – Collenchyma – Sclerenchyma DermalTissue • Cu=cle—prevents waterloss • Trichomes—small hairs(fuzzy) • GuardCells—gas exchange • Stomata—gas exchange • RootHairs—increase surfacearea VascularTissue • Xylem—containdeadcells,actslikeastraw • Transportwater – Tracheid – VesselElement • Phloem—containslivingcells • Transportsugar – SieveTubeElement – CompanionCells VascularBundleArrangement Monocots Dicots XylemandPhloem Xylem Phloem Epidermis–protec=onagainstwaterloss Func-onalPhloem-conductsugars awayfromleaftorestofplant VascularCambium-adds2°xylemand2° phloem Xylem-conductwaterandminerals upfromsoil Pith-waterstorage,defense Xylem • Transport=ssue – Water—upwardmo=on – Somenutrients • Greekfor“wood” – Butfoundthroughouttheplant • Deadcells XylemStructure • VesselElements(inangiospermsbut notingymnosperms) – Cylindrical – Connectedbyplateswithpores • Tracheids – Completelydeadatmaturity – Elongatednarrowtubeswithtapered ends – Actlikestraws – Reinforcedsecondarywalltoprovide morestructure SecondaryXylem • Accumulatesaswood • Olderlayersnolongertransportwaterand minerals – Heartwood • Outerlayerss=lltransportmaterial – Sapwood SecondaryPhloem • Sloughsoff Phloem • Transportsnutrients(madeduring photosynthesis) – “transloca=on” • Greekfor“bark” • Livingcells PhloemStructure • SieveTubeElements – Responsiblefortranspor=ngsugarthroughouttheplant – TransportmRNAandproteins – Lacknucleusatmaturitywithfeworganelles • Dissolveatthecellwall • Relyoncompanioncells – Containvacuoles – Called“sievetubemember”inangiosperms – Called“sievecell”ingymnospermsandferns • CompanionCells – Parenchymacells—makeuptheso\partsoftheplant VascularCambium • • • • Foundindicots Thelayerbetweenthexylemandphloem Secondaryxylem—growsinwardtowardpith Secondaryphloem—growsouttowardbark Howmanyyearsofgrowth arebeingshown? • Eachyear,secondary xylemandsecondary phloemareproduced. SpringoftheNEXTyear Winterofthatyear Fallofthatyear MidSummerofoneyear Whyisitnotagoodideatoremovethebarkofatree? Whenwouldyouwanttoexposethecambiumofatree? Growth ring Vascular ray Heartwood Secondary xylem Sapwood Vascular cambium Secondary phloem Bark Layers of periderm WaterTransportinCeleryLab
