LESSON 7: PLANT ADAPTATIONS - · PDF fileLESSON 7: PLANT ADAPTATIONS LEVEL ONE ... , the...
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65 LESSON 7: PLANT ADAPTATIONS LEVEL ONE Life is seldom ideal. We all live with situations that are difficult for us in some way. Some people face severe problems such as not being able to find enough food or clean water, living in extremely hot or cold climates, or having to deal with a chronic illness. Others of us live with milder limitations having to do with our age, our size, our family situation, the neighborhood where we live, the work our parents do, the personalities of our siblings, and so on. We don’t think of plants as having the same problems that we do, but to a large extent, they really do. They can experience malnutrition, extreme temperatures, unfriendly neighbors, competition for territory, “parents” who overshadow them, “siblings” who are more or less successful than they are, chronic and acute illnesses, and problems due to aging. Obviously, they can’t think about their problems like we can. All of their responses come not from their brains (which they don’t have) but from their pre-programmed DNA that allows them to adapt and survive. Let’s take a look at two of the most basic problems a plant might face. We could introduce these problems as a silly “Would You Rather...?” question. In the “Would You Rather...?” game, players are forced to choose between two bad options. For example, “Would you rather be trapped in outer space or at the bottom of the ocean?” No matter which you choose, the outcome will not be good. You must choose what you feel to be “the lesser of two evils,” and then explain your choice. The game is intended to encourage interesting discussions and hopefully bring some laughter along the way. If plants were playing this game, one of them could ask this question: “Would you rather have almost no water at all, or so much water that you are drowning in it?” Assuming that a plant had a brain and could think about this question, it would ponder the consequences of each option. Not having enough water would mean that as transpiration occurred, there would be no way to replace the water lost through the leaves. The plant would dry out and probably die. Being immersed in water would mean that the stomata (holes) in the leaves would be filled with liquid water, preventing the plant from “breathing,” causing the plant to die. Too much water might also encourage the growth of harmful bacteria. So which option is worse? It’s like choosing between dying of thirst and drowning. Two bad options! Some plants would definitely choose the “too little water” option. In fact, they live out that scenario every day and mange to survive. Desert plants have special adaptations that allow them to live in places that get less than 10 inches (25 cm) of rain a year. In deserts, rain is often seasonal, and months can go by with no rain at all. How is it possible for a plant to survive that long without water? Garden plants start wilting if they don’t get rain every week. A normal plant growing in a place with adequate rainfall has a constant flow of water going in through its roots, up through its stems, and out through its leaves. (Remember, the beginning of this process is actually the “out through the leaves” part. The loss of water in the leaves causes water to flow up through the stems, and finally come in through the roots.) If there is not a constant source of water available, this mode of living doesn’t work. What changes would have to be made to a plant’s anatomy in order to prepare it for life in a desert?
Transcript of LESSON 7: PLANT ADAPTATIONS - · PDF fileLESSON 7: PLANT ADAPTATIONS LEVEL ONE ... , the...
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LESSON 7: PLANT ADAPTATIONS
LEVEL ONE
Lifeisseldomideal.Wealllivewithsituationsthataredifficultforusinsomeway.Somepeoplefacesevereproblemssuchasnotbeingabletofindenoughfoodorcleanwater,livinginextremelyhotorcoldclimates,orhavingtodealwithachronicillness.Othersofuslivewithmilderlimitationshavingtodowithourage,oursize,ourfamilysituation,theneighborhoodwherewelive,theworkourparentsdo,thepersonalitiesofoursiblings,andsoon. Wedon’tthinkofplantsashavingthesameproblemsthatwedo,buttoalargeextent,theyreallydo.Theycanexperiencemalnutrition,extremetemperatures,unfriendlyneighbors,competitionforterritory,“parents”whoovershadowthem,“siblings”whoaremoreorlesssuccessfulthantheyare,chronicandacuteillnesses,andproblemsduetoaging.Obviously,theycan’tthinkabouttheirproblemslikewecan.Alloftheirresponsescomenotfromtheirbrains(whichtheydon’thave)butfromtheirpre-programmedDNAthat allows them to adapt and survive.
Let’stakealookattwoofthemostbasicproblemsaplantmightface.Wecouldintroducetheseproblemsasasilly“WouldYouRather...?”question.Inthe“WouldYouRather...?”game,playersareforcedtochoosebetweentwobadoptions.Forexample,“Wouldyouratherbetrappedinouterspaceoratthebottomoftheocean?”Nomatterwhichyouchoose,theoutcomewillnotbegood.Youmustchoosewhatyoufeeltobe“thelesseroftwoevils,”andthenexplainyourchoice.Thegameisintendedtoencourageinterestingdiscussionsandhopefullybringsomelaughteralongtheway.Ifplantswereplayingthisgame,oneofthemcouldaskthisquestion:“Wouldyouratherhavealmostnowateratall,orsomuchwaterthatyouaredrowninginit?”
Assumingthataplanthadabrainandcouldthinkaboutthisquestion,itwouldpondertheconsequencesofeachoption.Nothavingenoughwaterwouldmeanthatastranspirationoccurred,therewouldbenowaytoreplacethewaterlostthroughtheleaves.Theplantwoulddryoutandprobablydie.Beingimmersedinwaterwouldmeanthatthestomata(holes)intheleaveswouldbefilledwithliquidwater,preventingtheplantfrom“breathing,”causingtheplanttodie.Toomuchwatermightalsoencouragethegrowthofharmfulbacteria.Sowhichoptionisworse?It’slikechoosingbetweendyingofthirstanddrowning.Twobadoptions!
Someplantswoulddefinitelychoosethe“toolittlewater”option.Infact,theyliveoutthatscenarioeverydayandmangetosurvive.Desertplantshavespecialadaptationsthatallowthemtoliveinplacesthatgetlessthan10inches(25cm)ofrainayear.Indeserts,rainisoftenseasonal,andmonthscangobywithnorainatall.Howisitpossibleforaplanttosurvivethatlongwithoutwater?Gardenplantsstartwiltingiftheydon’tgetraineveryweek. Anormalplantgrowinginaplacewithadequaterainfallhasaconstantflowofwatergoinginthroughitsroots,upthroughitsstems,andoutthroughitsleaves.(Remember,thebeginningofthisprocessisactuallythe“outthroughtheleaves”part.Thelossofwaterintheleavescauseswatertoflowupthroughthestems,andfinallycomeinthroughtheroots.)Ifthereisnotaconstantsourceofwateravailable,thismodeoflivingdoesn’twork.Whatchangeswouldhavetobemadetoaplant’sanatomy in order to prepare it for life in a desert?
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LEAVES:Thisiswherethewaterlossproblemstarts.Thatpeskytranspirationprocessisconstantlyallowingwatermoleculestogoflyingoffintotheatmosphere.Canthisbeprevented?Couldwejustgetridoftheleaves?Maybe,butleavesarewherephotosynthesisoccurs,sotheplantswouldstarvewithoutphotosynthesis.Ifaplantdidnothaveleaves,itwouldhavetohavephotosynthesisoccurringsomewhereelse.Ormaybewecouldjustreducethesizeoftheleavesinsteadofgettingridofthemaltogether.Smallerleaveswouldmeanlesswaterloss.
STEMS:Whatchangescouldbemadetothestems?Couldphotosynthesisoccurhere?Couldthestemsbeadaptedforwaterstorageinsteadofsimplyholdingtubesforwatertransport?Ifso,thestemsmighthavetobecomeverylargeattimes.
ROOTS:Isthereanywaytomakerootsmoreefficientatgatheringwater?Shouldtherootsgodeeper?Orwoulditbebettertokeepthemshallowandnearthesurfacesothattheycanquicklysoakuprainwhenitcomes?Wouldhavingmoretinyroothairshelp?
Themostfamousofalldesertplantsisthecactus,ofcourse.Cactusplantslookliketheyhavenoleaves.Technically,theirsharpspinesareactuallyleaves,buttheseleaves are so thin that they lose almost no water at all. We saw a similar adaptation in pine trees. Pine needles are actuallyverythinleaves.However,sincepineneedlesaregreen,itiseasiertothinkofthemasleaves.Cactusspinesjustdon’tseemlikeleaves,butbotanistsassureusthatspinesareindeedhighlyadaptedleaves. Whatcouldpossiblybethepurposeofaleafthatcanhardly do photosynthesis and doesn’t initiate transpiration? Whatarecactusspinesgoodfor?Themainthingtheydoishurtlikecrazyifyougettheminyourskin.Sharpspineshelptoprotectcactifromthirstydesertanimalswhomightwanttoquenchtheirthirstwithabigbiteofjuicycactus
stem.Somebotaniststhinkthespinesmightalsohelptocollectwateratnight.Littledropletsofdewformonthespines.Thesedropletsrundownthespinestowardthestems,thentheyflowdownthestems,endingupatthebaseoftheplantwheretherootsnearthesurfacecanabsorbthemoisturequicklybeforethesuncomesup.
Thebodyofacactusistechnicallyastem.Mostcactiaregreen(oratleastgreen-ish),whichtellsyouthatthesebulkystemscontainchlorophyll.Whereverthereischlorophyll,photosynthesisisoccurring.Cactimustuseadaptedformsofphotosynthesis,however.Regularphotosynthesisrequiresaconstantsupplyofwaterandcarbondioxidefromtheair.The“downside”ofnothavingregularleavesisthatyoucan’tuseregularphotosynthesis.Thetypesofphotosynthesisdesertplantsusearecalled“C4”and“CAM.”(Regularphotosynthesisisknownas“C3”sinceitproduces3-carbonsugars.C4produces4-carbonsugars.“CAM”isanabbreviationforagruesomelycomplicatedwordthatevenscientistsdon’tliketousebecauseit’stoolong.Theyjustsay“CAM.”) Cactusstemshavetheabilitytostorealotofwater—enoughwatertokeepthecactusaliveduringdryseasonsthatlastformanymonths.Thebodyofacactususuallylookslikeitismadeof“pleats”thatgoinandout.Thisshapeallowsforeasyexpansionandcontractionwithoutanydisruptionoftherootsatthebaseoftheplant.Therootsystemofacactusisoftenveryshallowand
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extendsoutwardfromtheplantquiteadistance.Whenraincomes,thecactushasthousandsofroothairswaitingandreadyrightnearthesurface.Largecacticantakeinover100gallons(400liters)duringasinglerainstorm. Afewtypesofcactihaveverylongtaprootsinadditiontolotsofsurfaceroots.Thelongcentraltaprootcanbetwiceaslongasthebody(stem)ofthecactus.Thisdeeprootcanstorealotof water. Cactusstemshaveastructurethatotherplantsdonothave:bumpscalledareoles.Botanistsguessthatareolesaremostcloselyrelatedtothebranchesofregularplants.Itisfromtheareolesthatbothspinesandflowersgrow. Onelastimportantcactussurvivalstrategyistogrowslowly.Cactidon’tneedtobeinanyhurry.Growthtakesenergy.Aplant’senergycomesfromsugarsmadeduringphotosynthesis.Desertplantsarealreadyatadisadvantagewhenitcomestophotosynthesisbecausetheyhavetokeeptheirstomatashutalldaytopreventlossofmoisture.Growingslowlyreducestheneedforsugar.
Cactiarenottheonlytypeofplantsthatcansurviveindryclimates.Plantscalledsucculentsaresimilartocactiinmanyways,thoughtheyhaveactualleaves,notspines.Theleavesofsucculentplantsfeelthickand“juicy.”Thestemsareoftenverythickandcanstorewater.Somesucculentshavestemsandleavesthatarefilledwithagooeysubstancecalledmucilage (mew-sell-ahj).Themucilageactslikeaspongeandholdswater.Acommonsucculentplantthatmanypeoplerecognizeisthealoeveraplant.Somepeoplecallitthe“burnplant”becauseyoucanbreakopentheleavesandusethemucilagetosootheburnedskin.Themucilagemayfeelslimyandweird,butitdoesmakeyourskinfeelbetter.
Succulentleavesfeelliketheyarecoveredinawaxysubstance.Thisisbecausetheyare coveredinawaxysubstance.Wemetthiswaxysubstancebackinlessonfivewhensawthecrosssectionofaleaf.Thethintoplayerwascalledthecuticle.Allleaveshaveatleastatinybitofcuticle,butsucculentleaveshavealotofit.Cuticleisfairlywaterproof,soitkeepsmoisturefromgettingoutof(orgoinginto)theleaf. Anothercharacteristicofsucculentleavesisareducednumberofstomata.Thoselittlestomataholesarewhereairandmoisturegetinandoutofaleaf,soifyouhavefewerholesyouhavelessofaproblemwithwatermoleculesescaping.Succulentshavefewerstomatathanregularplants.Also,succulentstendtoclosetheirstomataduringthedaywhenthesunishotandevaporation(andthereforedehydration)willoccurquickly.Theyopentheirstomataatnight,whentheairiscoolerandevaporationislessofaproblem.
Thesestomatatricksareprettyslick,butthere’sadownsidetothem.Thereducednumberofstomataandthedaytimeclosingsalsomeanthatasucculentleafcan’ttakeinasmuchcarbondioxideasanormalleafcan.Likecacti,succulentsneedtousethosealternativeformsofphotosynthesis:“C4”and“CAM.”Intheseformsofphotosynthesis,carbondioxideisbroughtinatnightandthecarbonsaresnippedoffandstoredintheformofanacid.(Youcouldthinkofitlikecanningfood,perhaps?)Thesucculentcellshavetobeveryefficientwiththeircarbonatomsbecausethereisalimitedsupplyofcarbondioxide.
The bumps are areoles.
This beautiful succulent is called aeonium.
This is a photo of a real stoma.
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Onelastsucculentsurvivaltrickworthmentioningishair.Someplantsgrowhairsontheirleavesorstemsinordertoprovidesomeextraprotectionfromthewindandsun.Thehairsactlikealayerofinsulation,slowingdowntherateofevaporation.Oncolddesertnights,dewcancondenseonthehairsandperhapsasmalltrickleofwaterwillreachtherootsbymorning. Areallythicklayerofhairsprobablyalsofunctionsasawaytodeterinsectsfrombitingintotheplant.Theinsectcan’tgetitsmouthpartscloseenoughtothestembecausethehairsgetintheway.Thisfeaturecanbeseenonplantsintemperate(notsohot)areasoftheworld,notjustinsuperdryclimates.Youmighthavesomeplantswithhairystemsandleavesgrowingrightnearyou.Sunflowers,forinstance,haveveryhairystems.Theplantcalled“Lamb’sEar”hasleavessofuzzytheyfeellikeanimalears,notplantleaves. Plant hairs are not made from the same stuff that animal hairs are.Animalhairismadeof“dead”proteinmolecules.Planthairsaremadeoflivingplantcells.Planthairsareproperlycalledtrichomes,andtheyareextensionsofepidermiscells.(Remembertheupperandlowerepidermiscellsfromtheleafcrosssection?)Thesespecializedepidermiscellscangrowtobeverylongandthin.Somehavespecializedcellsatthetipthatcansecretestrong-smellingsubstances.Thestrongsmellofmostherbs(suchasmint)comefromsmellyoilsproducedbyglandcellsonthetipsoftrichomes. Let’sturnnowtotheotherterribleoptionforplants:drowningin
water.Toomuchwaterwillkillmostplants,buttherearesomeplantsthatareadaptedforlivinginwaterallthetime.Whatadaptationswouldaplantneedtohaveinordertosurvivebeinginwaterallthetime?Wouldthestomatabeaproblem?Wouldwaterstillflowupthexylemtubes?Wouldtherootsneedtobeindirt?
Therearemanytypesofaquaticplantsandtheiradaptationsarejustwhattheyneedfortheirspecificenvironment.Someplantshavetheirrootssubmergedinwaterallthetimewhiletheirleavesstayoutofthewater.Otherplantshaverootsandstemsunderthewaterandleavesthatfloatonthesurface.Themostextremewaterplantslivecompletelysubmergedallthetime. Whatadaptationswouldaplantneedtohaveinordertobeabletolivesubmergedinwaterallthetime?Woulditneedstomataorcuticle?Whataboutroots?Woulditbeabletomakeflowers?
Seagrassesspendtheirentirelifeunderthewater.Theylookandactverymuchlikeregulargrass.Theyevenhavethosepeskyrhizomesthatletthemusevegetativereproductiontospreadveryquickly.Thisisannoyinginyourgardenwhenthegrassstartstakingoveryourstrawberrypatch,butalongseashoresthisabilitytospreadquicklyisaverygoodthing.Seagrassesareaveryimportantpartofshorelineecosystems.Seagrassesreproduceusingflowersandseeds,too.Thepolleniscarriedbywaterinstead of wind.
Seagrassleaveshaveneithercuticlenorstomata.It’spointlesstotrytokeepwaterinoroutwhenyouaresurrounded
byitallthetime!Thecellsintheleavesareokaywithbeingsaturatedwithwaterallthetimeandthecellshavemicro-adaptationsthatletthemtakecarbondioxiderightfromthewater.Likeallleaves,seagrassleavesneedsunlightforphotosynthesis.Thismeansthatseagrassescanonlygrowinrelativelyshallowwater.Ifthewaterbecomescloudybecauseofpollution,thedeeperseagrasseswillstarttodieout.Dyinggrassmightnotsoundlikeabigdeal,butseagrassesoccupyaveryimportantplaceinmanyaquaticecosystems.Seagrassbedsarefilledwithallkindsofanimallife.Ifthegrassesdisappear,sodotheanimals. Seagrasseshaveanotheradaptationthathelpsthemtosurviveinthewater.Theyhave
Some trichome cells are long and skinny. The round tips make smelly oils.
A manatee eating seagrass. (USGS photo)
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microscopicairsacsintheirleavesandstemsthatactlikelittlefloaties,keepingtheleavesuprightinthewater.(Ifyoutakeseagrassoutofthewater,itdroopsoveryourhandlikeawetnoodle.Theleavesdon’thavestiffcentralveinslikeregulargrassbladesdo.Seagrassesneedtobeabletobendandflexand“gowiththeflow”inthewater.Iftheirleaveswerestiff,they’dgettornapartbythemotionofthewater.)Thetinyairsacsintheleavesandstemsprovidejusttherightamountofbuoyancysothattheleavesstayuprightinthewater,reachingtowardthesunlight. Waterplantsaresurroundedbywater,sotranspirationisnotnecessary.Cellscangetwhatevertheyneedbyosmosis.(Remember,osmosisiswhenmoleculesgorightthroughthecell’smembrane.)Thecarbondioxide,water,andnutrientsareabundantallaroundthecells,soxylemtubesaren’treallynecessary.Inmostwaterplants,thevascularbundlesareverymuchreduced,andinsomecasestheyarealmostabsent.
Aslightlylessdrasticsituationiswhenaplantisonlypartlysubmergedinwater.Thebottomhalfoftheplantstaysinthewaterwhilethetoppartisallowedtotouchtheair.Agreatexampleofaplantadaptedtothissituationisthewaterlily.Let’stakeaclose-uplookatalilythatholdstheworldrecordforthelargestleafintheplantkingdom:theAmazonlily.
FoundintheAmazonRiverinSouthAmerica,thislilycangrowleavesthatareupto8feet(2.5meters)across.Thesegiantleavesarealmostperfectlyroundandlooklikefloatingplates.Theyarequitestableandcansupporttheweightofsmallbirdsandanimals.Theirstrengthisduetoanetworkofstrongveinsontheundersideoftheleaf.Theirabilitytofloatisduetosmallairpocketsinsidetheveins.Inadditiontobeingstrong,theseveinscanalsobedeadly—theyarecoveredinsharpspines.Fishlearnveryquicklythatnibblinglilyveinsisabadidea! Thebottomsidesofthelilyleaveshavetwootherfeaturesthatareworthmentioning.Likeseagrasses,theyhavenostomataandnocuticle.Unlikeseagrasses,theseundersideshavelotsofredpigmentinthem.Theredpigmentmoleculeshelptocatchwavelengthsoflightthataremissedbythegreenchlorophyllpigmentsontop. Thetopsideofalilyleafisnothinglikethebottomside.It’sgreen,iscoveredwithwaxycuticle,andcontainsstomata.Thetopsideisadaptedtolivinginair,thebottomsidetowater.
These three different types of seagrasses all have leaves that fl ex and bend with the water currents.
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ThelifecycleoftheAmazonwaterlilysoundslikesomethingfromafantasystory.Itsflowersbloomforonlytwodays.Thefirstnightitblooms,theflowerisfemale.It’swhiteandsmellslikefragrantperfume,anodorthatscarabbeetlesfindirresistible.Oncetheflowerhasattractedbeetles,itclosesup,trappingthebeetlesinside.Duringthenight,theflowerchangesitsgenderfromfemaletomale,anditscolorfromwhitetopink.Italsostopsmakingperfume.Whenthefloweropensupattheendofthesecondday,thebeetlesarefreedfromtheirfloweryprisonbutarecoveredwithpollengrains.Theflowernolongersmellsgood,sotheyflyofftofindanotherwhitelilyflower,carryingthepinkpollengrainswiththem. Oncefertilized,theflowerclosesandfallstothebottomoftheriverwhereitformsaseed.Theseeddoesnotbegintogrowuntilthenextyear.LilyseedsusuallygerminaterightastheAmazonRiverisreachingitsannualfloodstage,withthewaterrisingseveralinchesaday.Thenewlysproutedwaterlilystemmustgrowatanunbelievablyfastrateinordertokeepits“head”abovetherisingwater.Thestemiscapableofgrowingupto20feet(7meters)tallinjustafewweeks.Whenthewatersstoprising,thelilystartsgrowinggiantleaves(lilypads). It’sthenabattleoflilyversuslily,witheachplantattemptingtodominateitsarea.(Siblingrivalryhappensevenamongplants!)Onceagiantleafhasspreaditselfoutoverthewater,anyplantunderneathitwilldiefromlackofsunlight.Asidebenefitofthissituationisthatalgaeisalsopreventedfromgrowing.Thisiswhywaterlilies(usuallyvarietiesotherthanAmazon)areplantedinoutdoorwatergardens.Peoplewouldratherlookatlilyleavesthanalgae“scum.”
Oneofthesmallestaquaticplantsonearthiscalled“duckweed”or“waterlentils.”Duckweedlooksliketinygreendotsfloatingonthesurfaceofalakeorpond.Theyarebrightgreenandlookveryclean.Truetoitsname,
ducksloveduckweed.Otherwaterbirdseatittoo,aswellaspeopleinsomepartsoftheworld.It’sagreatsourceofprotein,evenbetterthansoybeans,anditproducesmorestarchperacrethancorn!It’spossiblethatduckweedcouldbeturnedintoethanolfuel,justlikecornis.Somedayourcarsmightrunonfuelmadefromduckweed! Aduckweedplantconsistsofjustatinyleaf,withnovisiblestemsorroots.(Insomespecies,theleaveshaveverysmallroothairsdanglingfromtheunderside.)Ifduckweeddoesn’thavestemsorrootscanitstillbeclassifiedasaplant?Wedecidedwaybackatthebeginningoflessononethatthereareonlytworequirementsforbeingaplant:1)youmustdophotosynthesis,and2)youmustbemadeofmorethanonecell.Duckweedqualifiesonbothcounts.Infact,it’sevenclassifiedasanangiospermsinceitoccasionallyproducesflowers—thetiniestflowersintheplantkingdom,nolargerthanthewidthofapieceofthread!
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ACTIVITY 1: SIT LIKE A LUMP ON YOUR CHAIR OR COUCH AND WATCH VIDEOS
Thisactivityshouldnotbetoodifficult.Logontowww.YouTube.com/TheBasementWorkshopandenjoythevideosaboutdesertplantsandwaterlilies.
ACTIVITY 2: PLANT PUZZLE
Fillinthemissingwordsintheclues,thentransfertheletterstothenumberedslotsunderneaththepictures.Assumingyou’vefilledinthecluescorrectly,you’llfindoutthenamesofthesucculentplantsinthepictures.(We’recountingcactiassucculents.Sometimesthewordsucculentisusedasamoregeneralterm,withcactibeingasubcategory.)
1)Succulentshavefewer_____________________andmore_____________________.6818941311122654536Theyalsohavegooeystuffcalled________________________intheirstemsandleaves.52549328422)Cactihavebumpscalled_____________________ontheir_______________.5938749553)Desertplantsmustusetwootherformsofphotosynthesis:“___4”and“_________.”9053394)Thewaterplantcalled________________________looksliketinygreendots.Eventhough7128664857itdoesnothavestemsorroots,itisstilla_______________becauseitdoesphotosynthesisandismadeofmorethanonecell.86310
5)Duckweedisverynutritious.Likesoy,itisagoodsourceof_____________________andlikecorn,itisagoodsourceof__________________.47719962067494162566)Likeallplants,whenaduckweedflowerispollinated,a__________________isformed.354670247)Thistypeofanimallovestoeatseagrass:_____________________.7216558)Planthairsarecalled___________________________andoriginatefromthe5087136333___________________________layer.21933478429)The__________________sideofanAmazonlily_________isthecolor_________and371597812587961hassharp__________________ontheveins.88602610)Whenwaterevaporatesoutthroughtheleaves,causinganupwardflowofwaterfromtheroots,thisiscalled_______________________________________.73692740297776641411)Thealoeplantissometimesusedtotreatthistypeofinjury:____________6925812)___________________________plantshavevery_______________stems.Thislets9123438075304451themstorewatersotheycan_____________________indesertclimates.178248913)Thiswordrootmeans“naked”inGreek:_______________839812
Z
BS
S
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____________________cactus____________plant__________plant123456789101112131415161718192021
______plant____________cactus________plant__________plant222324252627282930313233343536373839
____________________________________404142434445465152535455565758596061____________________47484950626364656667
______________________________________________________686970717273747576777879808182838485909192939495969798 cactus________cactusplant 86 87 88 89
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LEVELTWO
Wenowturntothemacabre(darkandspooky)sideofplantadaptations—plantsthateatanimals,makepoisons,andparasitizeotherplants.We’llmeetseveralofthestrangestplantsonearth. Whatwouldcauseaplanttobecarnivorous?(“Carn”means“fleshormeat,”and“vor”means“eat.”)Plantsusephotosynthesistomakeallthefoodtheyneed.Theydon’tneedanoutsidesourceoffoodenergy.Whatelsedoesaplantneedbesidescarbondioxide,water,andsunlight?Thinkaboutachlorophyllmolecule.Wheredoesaplantgetthosenitrogenandmagnesiummolecules?Asmitosisoccursandplantsmakenewcells,theyhavetogettherawingredientsneededtomanufacturemorechlorophylls,plusmanyothertypesofmolecules.Someofthesemoleculescontainatomssuchassodium,phosphorus,potassiumandcalcium.Carbondioxideandwateronlyprovidecarbon,oxygenandhydrogenatoms. Undernormalconditions,planttakethesemineralsfromthesoil.Plantsdon’t“eat”dirt,buttheydotakemineralsoutofit.Ifthesoildoesn’tcontainenoughminerals,theplantswon’tbeabletogrowthereunlesstheyhavesomealternatemeansofgettingminerals.Onealternativeistogetthemineralsfromthebodiesofanimals(mainlyinsectsandspiders). ThemostfamousofthecarnivorousplantsistheVenus flytrap.It’snotuncommontofindtheseflytrapsforsaleingreenhousesinmanypartsoftheworld,butifyouwanttofinda“wild”flytrapgrowinginitsnaturalenvironment,youwillhavetogototheAmericanstateofNorthCarolinaandfindabogwithin60milesofthecityofWilmington.Bogsareplacesthatarewetandsoggyallthetime.Thebogswheretheflytrapsgrowhaveverylittlenitrogenandphosphorousinthesoil.Theflytrapsareoneofthefewplantsthatthriveinthesebogs.Theygetverylittlecompetitionfromotherplantsbecauseofthislackofmineralsinthesoil.Theflytrapsappreciatenothavinganyrivalsinthearea.Infact,Venusflytrapsappreciateanoccasionalwildfireonceinawhile,too,justasaback-uptoremoveotherplantsfromthearea! Theleafofaflytrapisthesnappytrapontheend.Thelongflatpartthatlookslikealeafisactuallythepetiole.Thepetiolesaretheprimarysiteofphotosynthesis.Aswementionedintheopeningparagraph,flytrapsdon’teatfliestogetenergy.Theyusephotosynthesisjustlikeallplantsdo.Theflytrapisafloweringplant,asyoucanseeinthepicture.It’sevenadicot.Soinsomeways,it’s a very normal plant.
Thehingedleafontheendhastwouniquefeaturesthatworktogethertocatchflies.Thefirstisasetofthreetrichomes(“hairs”)ontheinsideofeachlobe,whichfunctionasmotiondetectors.Thesetriggerswillcausethetraptoclosesuddenlyifoneofthehairsistouchedtwiceveryquickly,oriftwoseparatehairsaretouchedwithin20seconds.Thesecondfeatureistheabiltyofthetwolobestosnaptogetherinabout1/10ofasecond. Plantsdon’thavemuscles,sohowistheflytrapabletodothis?Scientistsarestillinvestigating,butitseemsthattheanswerinvolvesthesuddenflowofwaterintoandoutofcells.Protonsareakeytothisrapidmovementofwatermolecules.Asuddenincrease
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ordecreaseintheamountofwaterinacellchangesitsshape.Anoverallchangeinshapecanbeseeninaflytrapleafafteritcloses.Whiletheleafisopen,thelobescurveoutward;afterclosingtheyarebentinward. Oncethelobeshaveclosedandthepreyistrapped,digestiveglandsonthesurfaceofthelobesbegintomakedigestiveenzymes.Basically,theclosedleafbecomesastomach!Theleafstaystightlyshutforabouttendays.Duringthistimethebodyofthepreyisreducedtoapuddleofmolecules,withmaybesomebitsofoutershellleftover.Afterthetrapopens,therainwillwashawaytheremainsofthemeal.Ifthepreyistoosmallandmanagestoescape,thetrapwillre-openinabout12hours.
Almostaswell-knownastheflytrapsarethepitcher plants.Theirleavesareshapedinsuchawaythata“pitcher”isformed.Likewaterpitchers,theseplantpitcherscancollectandholdwater.Pitcherplantsattracttheirpreyusingcolors,odors,andnectars.Theunsuspectingbugscrawlalongtheslipperyedgeofthepitcherandinevitablyslipandfallintothewaterpitbelow.Iftheymanagetoswimovertotheedgeofthepitcherandtrytoclimbout,theyfindthewallsofthepitcherextremelyslipperyorcoveredwithdownward-pointinghairsthatpreventthemfromescaping.Thebugsdrowninthewaterandtheirbodieseventuallydissolvewithsomehelpfromdigestiveenzymessecretedbytheplantcells.
Thepitcherplantsshownintheillustrationabovearethekindyoufindgrowinginthewarm,humidpartsoftheAmericancontinents.AverydifferenttypeofpitcherplantgrowsinIndonesia,southChina,andnorthernAustralia.Thescientificname(thegenus)forthesepitchersisNepenthes.ThisnamecanbetracedbacktoabookwrittenbyCarlLinnaeusin1737.ItcomesfromGreekmythology(Homer’sOdyssey),inastorywhereanEgyptianqueengivesHelenamagicpotionthatcauseshertoforgetallhersorrows.(“Ne”means“not,”and“penthe”means“grief.”)CarlLinneausexplainshischoiceofthisnameforthisplant: If this is not Helen’s Nepenthes, it certainly will be for all botanists. What botanist would not be filled with admiration if, after a long journey, he should find this wonderful plant. In his astonishment past ills would be forgotten when beholding this admirable work of the Creator!
TheNepenthesdoesnothavetorelyonraintofillitstraps.Itproducesathickfluidthatmakesescapeimpossiblefortheunluckyvictimsthatfallintoit.EvensmalllizardsandmammalscandrowninNepenthespitchers.However,afewspecieshavemanagedtooutwittheNepenthesandareabletostealsomeofitsfood.Carpenterantsliketonestinsidethetendrilsfromwhichthepitchershang.Thetendrilsarehollowsothisdoesnotharmtheplant.Theantsabletoswiminthepitcherfluidandwillworktogetherforhourstopulldeadpreyoutofthetrap.(Yes,theantsarecarnivorous,too!)Theplantactuallybenefitsfromthislivingsituationbecausetheantscleanupafterthemselvesandleavetheedgesofthepitcherspotless.Pitchersinhabitedbyantssurvivelongerthanthosethatare not.
Insomepartsoftheworld,theNepenthesiscalledthe“monkeycup.”Monkeysandlargeapesareknowntodrinkfromthesecups.(Ants?Yum,yum!)
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Anotherlargefamilyofcarnivorousplantsisthesundews.Thesundewshavetrichomesontheirleavesthatproducedropletsofclearstickyliquid.Theylookabitlikewaterdroplets,asifdewdropletshadformedonthetipsofthetrichomes.Thedropletssparkleinthesun.(The“sun”partofthenamecouldalsocomefromthefactthatthesundewsaresaidtohaveflowersthatturntowardsthesun.) Thedropletsproducedbythesundew’strichomesarebothsweetandsticky.Insectsareluredinbythesweetnessandtrappedbythestickiness.Aftertheinsectisstuck,thetrichomesbegintocoilaroundit,trappingitevenfurther.The
motioncanoccurquickly,withthetrichomesreactinginamatterofseconds.Withinseveralminutes,thewholeleafcanbecompletelycurledup.Digestiveglandsontheleavesthenreleaseenzymesthatdissolvethebodiesoftheinsects,eventheirtoughoutershell. Otherthantheirabilitytotrapanddissolveinsects,thesundews(likeallcarnivorousplants)arenormalfloweringplants.Theydophotosynthesisandtranspiration,theymakeflowersthatgetpollinatedbyinsects(differentspeciesthantheonesthatgettrapped)andmakeseedsthatgrowintonewplants.
Thelastcarnivorousplantonourlististhebladderwort. Thisplanthasdoubleadaptations.Notonlyisitcarnivorous,itisalsoaquatic.Inmostbladderworts,theonlypartoftheplantthatsticksupabovethewateristhestemthathasflowersonit.Theflowersareshapedabitlikesnapdragonsandcomeinawidevarietyofbrightcolors.
Thebladdersaretinylittlesacsthatgrowamongtheunderwaterleaves.Howtiny?Onaverage,theyareonlyabout1/4inch(1/2cm)indiamenter.Thewordbladderisaverygeneraltermthatmeansawater-filledorair-filledbag.Thecorrectnameforthebladderinyourbodyistheurinarybladder.Thewordbladderitselfdoesn’thaveanyconnectiontourine.Inthebladderwort,thebladdersarepouchesthatactashigh-speedtraps.Theycatchaquaticanimalssmallenoughtofitinsidethetrap.Pondwaterisusuallyfilledwithsemi-microscopiccrustaceans(relatedtocrabs)andinsectlarvae.
Thebladdershaveadesignthatallowsthemtotemporarilyforcetheirshapetocurveinward,causingstructuraltensionthatisabitlikepullingbackaspring.(Remember,plantsdon’thavemsucles,sothismovementiscausedbywaterandmineralsflowinginandoutofcells.)Thetraphassometriggerhairsaroundtheopening.Whenasmallanimalbumpsintothetriggerhairs,theshapeofthetrapsuddenlypopsbacktoits
normalopenstate,causingwatertorushin.Theanimalissweptalongwiththemini-currentandissuckedintothetrap.Thetrapcansnapshutinonly1/10,000ofasecond! Asyoumightguess,therearedigestiveglandsinsidethetrapthatdissolvetheanimal’sbody.Whendigestionisfinished,thetrapcanejecttheremainsandresetitself,pullingitsshapeinwardagain.
The things that look like roots are actually leaves. Both leaves and bladders remain under the water all the time. Only the flower sticks up out of the water. The plant does not need roots because the leaves are surrounded by water.
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Somebotaniststhinkofaplant’sabilitytomaketoxins(poisons)asanadaptationbecauseithelpstheplantsurvive.Plantshaveveryfewwaystoprotectthemselvesfromgettingeaten.Remember,plants“want”tosurvive,too,justasmuchasanimalsdo.PlantDNAisengineeredtocausethemtotrytoreproduceasmuchaspossible,andtoadaptthebesttheycaninordertothriveintheirenvironment.(Infact,inapastchapter,weaccusedthemofbeingbentonworlddomination!)
Toxinsareaveryeffectivewayforaplanttomakeitselflesslikelytobeeaten.Aplant’sprimaryenemiesareinsects,sothetoxinsarereallytargetedatthem,notatanimalsorhumans.Since
insectsareverysmall,ittakesonlyasmalldoseofthetoxintokillthem.Thedosethatkillsabugwon’tdomuchdamageatalltoalargeanimaloraperson.However,therearesomeplantsthatproducetoxinsstrongenoughtodamageevenalargemammal. Itwouldbeveryboring(orperhapsalittlescary)foryoutoreadalistoftoxicplants,sowe’lljustlookattwoplantsthatplayedapartinGreekandRomanhistory.
Perhapsthemostfamouspoisonousplantinhistoryisthehemlock.TheGreekphilosopherSocrateswasforcedtodrinkacupofpoisonhemlockaspunishmentforhis“impiety”(meaninghewasteachingyoungpeopletothinkforthemselvesinsteadofjustacceptingwhateverthemembersoftherulingclasstoldthem).Thishemlockplantisnotrelatedtothetreecalledthehemlock.Theyareentirelydifferent.Thescientificname(genus)forSocrates’hemlockis Conium.ThiswordcomesfromtheGreekword“konas,”meaning“towhirl.”Apparently,beingdizzy(feelinglikeyouarewhirling)isoneofthesymptomsofamildcaseofhemlockpoisoning.
Thescientificnameofthisplant,Atropa belladonna,soundsbeautiful,butit’scommonnamestellyouallyouneedtoknowaboutit:“devil’sberries,”or“devil’sherb.”Morerecently,ithasbeencalled“deadlynightshade.”Itbelongstothesamefamilyofplantsasthetomatoandthepotato(solanaceae,the“nightshades”).Thename“belladonna”comesfromItalianandmeans“beautifulwoman.”Whenthejuicesofthisplantareusedaseyedrops,theycausethepupilstodilate.AncientItalianwomenlikedtohavetheirpupilsdilatedwhentheymetanattractiveyoungman.Theythoughtthismadethemlookmorebeautiful.
Whengroundupandmixedintoapotion,thisplantdoesmorethandilateyourpupils—itkillsyou.ThewivesoftheRomanemperorsAugustusandClaudiusareknowntohaveusedthisplanttopoisontheirenemies.Beforetheydied,the
victimswouldhaveexperiencednotonlydilatedpupilsbutalsomentalconfusion,rashes,headache,lossofbalance,blurredvision,racingheart,sweating,hallucinationsandconvulsions.Notfun. Interestinglyenough,cowsandrabbitscaneatthisplantandhavenoilleffects.Fortherestofus,ahandfuloftheseberriescankillus.Sincetheberrieslookprettyandtastesweet,thisisadangerforsmallchildren.Fortunately,treatmentisavailableifyougettoamedicalfacilityquickly.AchemicalproducedbytheAfricancalabarbeanplantcanreversetheeffectsofthebelladonnatoxin.Butdon’ttaketoomuchofthisbeanchemical,becauseinhighdosesthiscurecanbetoxic,too.Thecalabarbean’stoxinisconsideredtobeoneofthemostpotentintheplantkingdom.
A GENERAL GUIDELINE FOR AVOIDING POISONOUS BERRIES: Don’teatanyberriesyoufindgrowinginthewildiftheyhaveasimple,roundshape.Berriesthatarelumpy,likeraspberries,areneverpoisonous.Somesmoothberriesareokay,butlotsofthemaretoxic.Don’ttakechances—juststayawayfromsmoothberries!
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Ourtourofthecreepysideofbotanyendswithalookatplantsthathavebecomeparasites. Aparasiteisanyorganismthatmustliveinoronanotherorganism.Manyparasitesendupharmingtheirhosttosomedegree,butnotsomuchthattheykilltheirhost—oratleastnotuntiltheparasitehashadachancetoreproduce.Wetendtohaveverynegativefeelingsaboutparasites,butaswewillsee,someparasiticplantscanbebeneficialtotheecosystemtheylivein.
Themostwell-knownparasiticplantisthemistletoe,theplantthathasbeenpartofChristmascelebrationsinwesternculturesforhundredsofyears.Abranchofmistletoeishungatthetopofadoorwayorsuspendedfromtheceiling.Coupleswho“happen”tocrosseachother’spathsunderthemistletoearepermittedakiss.Foreachkiss,aberryispluckedoffthebranch.Whentheberriesrunout,sodothekisses.
Youdidn’tknowmistletoewasaparasite?Mostpeopledon’t.Thename“mistletoe”(originally“mistiltan”)mostlikelycomesfromtheAnglo-Saxonwords“mistel”meaning“dung,”and“tan”meaning“twig.”Sothatmakestherealnameforthisplant“dung-on-a-twig.”Thedunginquestioncomesfrombirds.Birdseattheberries,andsomeoftheirdroppingfallontreebranches.Mistletoeseedshappentobeverysticky,sotheyquicklyadheretothebranch.Whentheseedsgerminate,theycangrowforawhileinthebirddropping,asifitwasdirt.Asquicklyastheycan,though,thebabymistletoeplantsstartputtingoutspecial“roots”calledhaustoria (hoe-STORE-ee-ah).Thehaustoriasomehowgrowtheirwaythroughthetree’sbarkandgetintothesapwoodwherethelivingxylemandphloemtubesare.Theyputtheirthinroot-liketubesintothetree’sxylemandphloem,asifputtingadrinkingstrawintosomeoneelse’sglass.Themistletoeslurpsaway,suckingwater,mineralsandsugarsfromthetree’svascularsystem.Thus,themistletoeispermanentlyattachedtoatree,insteadofgrowingintheground. Themistletoeiswhatbotanistscalledahemiparasite(“hemi”
meaning“halfway”).Theleavescanstilldophotosynthesis,soitisnotcompletelyreliantonthehosttree.Atfirst,thetreehardlynoticesthemistletoeandisn’tespeciallybotheredbyit.Ifrainfallisadequate,thereisenoughwaterforbothplants.However,asthemistletoegrowslargerandlarger,thereisagreaterpossibilitythatthetreewon’tbeabletokeepupwiththeincreasingdemandsthemistletoeplacesonit.Sometreesdoeventuallydiefrommistletoeinvasion,and,ingeneral,gardenersseemistletoeasathreat.Theyusuallypruneoffanytreebranchesthatshowmistletoe infestation.
Onlyrecentlyhaveresearchersdiscoveredthatinsomeplaces(Australiabeinganotableexample)somespeciesofmistletoearequiteabenefitto
thenaturalenvironment.Thoughmistletoeberriesaremildlypoisonoustohumans,birdslovethem.Areaswithalotofmistletoewillhaveadensepopulationofnestingbirds.Also,theleavesandyoungshootsofmistletoeareafavoritesnackforcertaintypesofanimals.Thus,areaswithmistletoetendto have more wildlife than areas without mistletoe. Biodiversity(thepresenceofmanydifferentformsoflifeinsteadofjustafew)isconsideredtobeagoodthing.Ecologistsallovertheworldareinagreementthatit’shealthyforanecosystemtohavelotsofdifferentspecieslivingtogether.
Otherparasiticplantsarewhatscientistscallobligate parasites.Theword“obligate”isrelatedtothewords“obliged”and“obligated.”Theseparaitesarecompletelydependentupontheirhostplant.Infact,theseplantshavelosttheabilitytodophotosynthesis.
A mistletoe starting to grow on a tree branch.
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]
Umm...well,howelsecanweclassifythem?They’renotfungi,bacteria,animalsorsingle-celledorganisms.Theymakeflowerswithpistilsandstamens—that’splant-like.Botanistsguessthatonceuponatimetheseplantsdiddophotosynthesis.Oncetheystartedfeedingonotherplants,theirneedforphotosynthesisdisappeared.Thecellssomehowsensedthisandstoppedmakingchlorophyll.Thisisjustaguess,ofcourse,asnoonewastheretowitnessthiswhenithappened.It’sjustatheory.However,thepossibilitythatthiscouldhavehappenedgivesuslicensetogoaheadandclassifyobligateparasiticplantsasplants.
ThemostfamousobligateparasitegrowsontheislandsofBorneoandSumatra.ItsscientificnameisRafflesia, (andmanypeopleusethisname),butitisalsocommonlycalledthe“carrionflower.”“Carrion”isapolitenamefordeadanimals.Yes,thisflowerstinkslikerottinganimalcarcasses.Why?Becauseanyinsectcanpollinateaflower.Itdoesn’thavetobecutelittlebutterfliesandbumblebees.Inthiscase,thestinkingflowerdrawsflies.Thefliesarefooledintothinkingthatthereisrottingmeatinsidetheflower,andpollinationisaccomplished.
TheRafflesiaholdstheworldrecordforbeingthelargestflowerintheworld—whichiskindoffunnywhenyoulearnthatthefloweristheonlypartthisplantreallyhas.Ithasnoleaves,nostemsandnoroots!(Atleastyouknewthatthosepartsaren’tincludedinthedefinitionofwhatmakesaplantaplant.)TheonlyotherparttheRafflesiahasisanetworkofhaustoria.Thehaustoriaareembeddedintotheveinsofavineplant,and
areinvisiblefromtheoutside.TheonlytimeyoucanbesuretheRafflesiaplantisthereiswhenitputsoutaflowerbud.Otherwise,youneverseethisplant!
Oursecondandlastobligateparasiteisthe“snowflower.”(Thebudsoftenpopupearlyintheyear,pokingupthroughthesnow.)LikeRafflesia,thistypeofplanthasnoleaves,nostemsandnoroots.Itconsistsofnothingbuthaustoriathreadslivinginsideafungusthatlivesonotherplants.Sincetheseplantsliveonafungus,somepeopleliketocallthem“fungusflowers.”Thesnowflowertakesitsnourishmentfromafungusthatistakingitsnourishmentfromaplant.Soindirectly,thesnowflowersarefeedingonaplant,butthroughthefungus.Verystrange,indeed. These snow flower buds were found in Yosemite
National Park in California.
Picture credits: Rafflesia by ma_suka on Wikimedia Commons, snow flower by Walter Seigmund, posted on Wikipedia article: Sarcodes.
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ACTIVITY 1: “O” THAT RAGWORT IS A PROBLEM!
Ragwortisawildflowerintheasterfamily(samefamilyasdaisies).Ithasprettyyellowflowersandlooksnicegrowingbytheroadside.ItisnativetoNorthernEurope,butcannowbefoundinplacesallovertheworld,includingAustralia,NewZealand,Argentina,India,northernAfricaandsomestatesinAmerica.Therearecertainmothsandfliesthatlovetofeastontheleavesandnectar.Infact,theywon’teatanythingelse.Theseinsectsdon’treflecttheopinionsoftheanimalkingdomingeneral,however.Ragwortisverybitterandmostanimalswon’twillinglyeatit.
Farmersallovertheworldareonamissiontotrytomakethisplantextinct(muchtothedismayofinsectenthusiasts).Thebittertasteofragwortisduetotoxins(poisonouschemicals)itproduces.Thesetoxinshelptheplantbykeepingitsafefromhungryanimals.However,astheplantdriesout,thetoxicchemicaltastelessbitter.Ifdriedragwortgetsmixedinwithhorseorcow’shaysupply,theanimalwon’tbeabletodetecttheragwortinitsfood.Theywillaccidentallyeattheragwortandthetoxinswillgetintotheirbloodstreamandpoisontheirlivers,makingthemverysick.Insomeplaces(suchastheUKandsomeUSstates)ifyoufindragwortgrowingonyourpropertyyouarerequiredbylawtodestroyit. Onewayyoucanidentifyragwortisbycountingthepetalsofitsflowers.Ragwortflowershave13petals.Therearen’ttoomanythingsinthenaturalworldthatcomein13’s.Oneofthefewplaceswherethenumber13showsupinflowerpetals.Othercommonpetalnumbersare4,5,8,10,and21.Mathematiciansthinkitisinterestingthatpetalnumbersroughlycorrespondto“Fibonacci”numbers:1,2,3,5,8,13,21,34...(addthetwopreviousnumberstogetthenextone).
Thisragwort’s13petalscorrespondto13botanical“rootwords”fromLatinorGreek.Theeasypartisthatalloftheserootwordsendintheletter“O”whichalreadyappearsinthecenteroftheflower.Fillintherestofthelettersstartingattheoutsideofthepetalandgoingtowardsthe“O.”Youmayhavetoturnyourpapersidewaysandupsidedown!(Ifyouneedahint,apagenumberisgivenwhereyoucanfindtheanswer.)
1)light(pg 1) 2)verysmall(think of a scientific instrument that lets you see very small things)3)green (pg 8)4)middle(pg 38)5)one(pg 31)6)turn(pg 36)7)tree(pg 40)8)life(think of the branch of science that studies life)9)flower(pg 44)10)naked(pg 50)11)vesselorcontainer (pg 52)12)yellow(pg 39)13)airorbreath(pg 8)
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ACTIVITY 2: MORE VIDEOS! (unless you watched them already)
Getcomfy,gotowww.YouTube.com/TheBasementWorkshop,andwatchsomefascinatingvideosoncarnivorousplants.
ACTIVITY 3: TRUE OR FALSE?
Canwetrickyou?Seeifyoucandeterminewhethereachstatementistrueorfalse.
1)___Flytrapscansurvivewildfires.
2)___Bogshavemineral-richsoil.
3)___Variousspeciesofflytrapsliveallovertheworld.
4)___Flytrapleaveshavenopetioles.
5)___Flytrapshavemusclecells.
6)___Nepentheshaveparasiticantsthatdestroytheirpitchers.
7)___Nepentheswerenotdiscovereduntilthe20thcentury.
8)___Allcarnivorousplantshavedigestiveglands.
9)___Pitcherplantscanbefoundgrowingonseveralcontinents.
10)___Nepenthesplantshaveasymbioticrelationshipwithaparticularspeciesoftropicalspider.
11)___Sundewtrichomescanmove.
12)___Carnivorousplantsproducepoisonouschemicalstoparalyzetheirprey.
13)___Thebladderwort’strapisprobablythefastest-actingmechanisminnature.
14)___Bladderwortshavenoroots.
15)___Bladderworttrapscanbeusedonlyonce.
16)___Socratesdiedbydrinkingapotionmadefromthehemlocktree.
17)___AConiumplantmakescones.
18)___Someanimalscaneatdeadlynightshadeandsurvive.
19)___Sometimesanimalsarenotbotheredbyplanttoxinsthatarefataltohumans.
20)___Nevereatwildraspberries.
21)___Themistletoeplantdoesnothaveroots.
22)___Ahemi-parasiticplantcanstilldophotosynthesis.
23)___Mistletoeplantsruinwildhabitats.
24)___TheRafflesiahasonlytwoparts:haustoriaandflowers.
25)___“Snowplants”arereallyatypeoffungi.
This is a species of pitcher plant called the cobra lily.
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LESSON 7Level1Activity1:1)stomata,cuticle2)areoles3)C4,CAM4)duckweed,plant5)protein,starch6)zygote7)manatee8)trichomes,epidermis9)bottom,pad,red,spines10)transpiration11)burn12)succulent,bulky,survive13)gymno PLANTSfromlefttoright,toptobottom:Firstrow:agave,brain,cocoon,stoneSecondrow:ice,pencil,aleo,zebraThirdrow:pricklypear,yucca,henandchicksFourthrow:saguaro,barrel,organpipe,curiosityLevel 2Activity1:1)photo2)micro3)chloro4)meso5)mono6)tropo7)dendro8)bio9)antho10)gymno11)angio12)xantho13)spiroActivity2:1)T2)F3)F4)F5)F6)F(pitcherisnotdestroyed7)F8)T9)T10)F11)T12)F13)T14)T15)F16)F(notthehemlocktree,butrathertheconiumhemlock)17)F18)T19)F20)F21)T(haustoriainsteadofroots)22)T23)F24)T25)F
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LESSON 7
1) FUN GAME: “Don’t Sink the Lily Pad!”
You will need: •Aluminumfoil •Apanorlargebowlofwater(severalinchesdeepisbest) •Scissors •Alargebowlofpennies(acoupleofdozenforasmallpad,severalhundredforapadthatisthesizeofadinnerplate)Youcouldalsouseddriedlimabeansorothersmallobjects.
How to prepare: Cutthreefoilcircles:asmallone(justafewinchesacross),amedium-sizedone(morelike4or5inchesacross)andalargeone(7to10inchesacross).FolduptheedgestomakeitlooklikearealAmazonlilypad.Refertothepictureinthechaptertoseethatthesepadshaveaverysteep“lip”allaroundtheedge.(Tip:Thehigherthelip,themorepenniesyouwillbeabletoplaceonthepadbeforeitsinks.)
How to play: Placethesmallestpadinthepanofwater.Itshouldfloatverywell.Lettheplayerstaketurnsplacingpenniesonthepad.Theideaistobeabletoplaceapennywithoutsinkingthepad.(Youcouldpretendthatthepenniesarefrogsorbirdsthatmightbefoundsittingonalilypad.)Thepersonwhosepennysinksthepadistheloser.(Youcanavoidhavingaloserbyjustmakingitfuntoseehowmanypennieseachlilypadwillhold.)Asthegameprogress,theplayerswillstartseeingstrategy—howtoaddpennieswithoutupsettingthebalanceofthepad.Playerswholikephysicalsciencewilllikethisgame. Aftertryingthesmallpad,moveuptothemediumpad,thenthelargepad. Duringthegame,asktheplayerswhattheynoticeabouthowthepadholdsweight.Whathappenswhenthepadfinallygivesway?Whereistheweakestpointonthepad?(Usuallythelowestpointonthelip.) Asanadditionalinvestigation,punctureasmallholeinoneofthepadsandtryitagain.Howmuchdifferencedoesasmallholemake?Punctureafewmoretinyholes.Anydifference?Whataboutalargehole?
2) MAKE A PAPER MODEL THAT SHOWS HOW A CACTUS STEM EXPANDS
You will need: •Paper •Scissors •Tape
Cuttwolongstripsofpaper(fromthelongsideofapieceofpaper).Foldthembackandforth(“accordion”style).Tapetheendstogetherandadjusttheshapesoitlookslikeoneinthepicture. Experimentwiththemodel.Demonstratehowacactusisabletoexpandsuddenly.
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3) PLAY A GAME ABOUT POISONOUS PLANTS: “Where Sheep May Safely Graze”
ThenameofthisgamecomesfromapieceofmusicwrittenbyJ.S.Bach(CanonNo.208).Heprobablywasn’tthinkingaboutpoisonousplantswhenhewroteit,butthetitlewasjusttootemptingtoresist. Theboardisdesignedfor1-4players,soifyouwillhavemorethan4players,maketwocopiesofthegameboard. Allplayerscanstillplayasagroup,butonseparateboards.
You will need: •Copiesofthegameboardpiecesandcopiesofthesheeptokens(onesheepperplayer) •Tape(agluestickmightalsobehelpfulforassemblingthesheeptokens) •Scissors •Optional:coloredpencilsormarkerssoplayerscancolortheirsheepinordertoidentifyit
How to set up the game: Tapetogetherthetwogameboardpages.Cutout,foldandassemblethesheeptokens.Eachplayershouldeitherwritehisnameonthesheep,orcolorthefleecesothathewillbeabletokeeptrackofhissheep.
How to play the game: Theobjectofthegameistogetyoursheepacrossthelongmeadowwithouteatinganypoisonousplants.Thiswillbedifficultbecausethreeoutoffourplantsineachrowaretoxictosomedegree.Onlyoneisconsideredbybotaniststobeedible.Notallthetoxicplantsareequallytoxic.Somewilljustcausestomachupsetorheadaches,otherswillkillyou.Aswithallthings,“Thedosemakesthepoison,”asParacelsusstatedbackinRenaissancetimes.Inmostcases,theamountyoueathasalottodowiththeoutcome.Eachplanthasbeengivenanumericalestimateofhowtoxicitis,usingascaleof1to3.(Thisisnotanofficialnumberyou’llfindanywhere.Thesenumberswerecreatedforthisgameandshouldnotbeconstruedasscientificallyvalidtoxicityestimates.)Edibleplantshaveatoxicityscoreof0,sothegoalistoendupwithascoreascloseto0aspossible.
Disclaimeratthispoint:Eventhoughthetokenisasheep,we’veerredonthesideofchoosingtodefineedibilitybyhumanstandards,notgrazinganimalstandards.Inmostcases,humansandanimalswillreactinasimilarmanner,butiftherewasanydiscrepancy,thehumanfactorwasgivenmoreconsiderationsincetheplayersarehumanswhomightfindthisinformationhelpfulatsomepointinthefuture.
Thisgamerequiresaleader(mostlikelytheteacher/adultincharge,butitcouldbeastudent,especiallyifyouhaveanolderstudentandsomeyoungerones).Theleaderwillgivethecorrectanswersaftereachmoveandwillalsobeabletoaddsomeextrainformationathis/herdiscretionfromtheextrainfosheet.
Allplayersmoveatthesametime.Theleadercallsoutthenumberoftherowthesheepwillbegrazing,movingfrom1to12.Theplayersthenplacetheirsheepontheplantinthatrowthattheyhopeisedible.Afterallsheephavebeenplaced,theleaderreadstheanswersandgivesthetoxicityratingforeachplant.Theplayerswritedowntheirscoreforthatrow.Astheyprogressuptherows,theykeepaddinguptheirpointssothatafterrow12theywillhaveafinalscore.Thelowestscorewins.
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azalea hibiscus rhododendron hydrangea
gooseberries asparagusberries pokeweedberries yewberries
tulipbulbs orchidbulbs daffodilbulbs hyacinthbulbs
maple tree leaves
dogwoodtree leaves
cherrytree leaves
oaktree leaves
rawkidneybeans rawlimabeans rawgreenbeans rawMungbeans
cherrypits grapeseeds apple seeds pear seeds
Where Sheep May Safely Graze
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azalea hibiscus rhododendron hydrangea
gooseberries asparagusberries pokeweedberries yewberries
tulipbulbs orchidbulbs daffodilbulbs hyacinthbulbs
maple tree leaves
dogwoodtree leaves
cherrytree leaves
oaktree leaves
rawkidneybeans rawlimabeans rawgreenbeans rawMungbeans
cherrypits grapeseeds apple seeds pear seeds
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potato leaves
tiger lily
violets
ferns
whitesnakeroot
wildcarrots
Threeoftheplants(orplantparts)ineachrowaretoxic.Oneisedible.
Goodluck,sheep!
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Trimoffthetopofthispagethentapeorgluethispagetothebottomofpreviouspage.
potato leaves
potato stems
greenpotatoes red potatoes
tiger lily
lily of the valley Jack-in-the-pulpit callalily
violets buttercups foxglove larkspur
ferns ivy holly cattails
whitesnakeroot jimsonweed ragwort nettles
wildcarrots
dandelion leaves
rhubarb leaves
tomato leaves
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Where Sheep May Safely Graze
Thispageisanextraincaseyouwanttomakeyourowngame,oraddadditionalrowstotheotherpages.
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potatoleaves(1)PotatoesbelongtotheSolana-ceaefamily,thenightshades.Allnightshadesproduce
solaninechemicals,atleasttosomedegree.Thischemicalismostabundantinthegreen
parts of the plant.
potatostems(1)
Sincepotatostemsaregreen,theycontainsomesolanine,achemicalthatcanaffectboththedigestivesystemandthe
nervoussystem.Cookingdoesnotdestroythischemical.
greenpotatoes(1)
Eatingafewbitesofgreenpotatowon’tmakeyouterriblysick,buteatingalotofthemisn’tgoodforyou.Thegreencolorindicatesthepresenceofsolanine,atoxicchemical.
redpotatoes(0)
Thetubersofpotatoplantsdonotcontainmuchsolanineaslongastheyarewhiteorredin
color.
tigerlily(0)
Tigerliliesareedibleandaresometimesusedtogarnishsal-adsanddesserts.Theybelongtothefamilyofdaylilies,whicharechemicallydifferentfromotherplantswecalllilies.
lilyofthevalley(2)
Thoughitlooksgreatinyourflowergarden,allpartsofthisplantcancauseabdominalpain,vomiting,andreducedheartrate.Eatingalargeamountcanbedeadly.
Jack-in-the-pulpit(1.5)Thisplantcontainssaponins,whichcausesevereirritationtothemouth,throatandstom-ach.Inseverecases,swellingcausesproblemswithbreath-ing.Whencookedproperly,the
rootcanbeedible.
callalily(3)Thistypeoflilycontainsoxalicacid(alsofoundinrhubarbleaves)andcausesdigestivedistress.Theacidcanaffectotherorgans,also,andadoseofaslittleas5gramscanbe
fataltosmallchildren.
violets(0)
Violets are often used to add colortoagreensalad.They
arehighinvitaminC.
buttercups(1)
Theselovelyflowerscanbeadangertograzinganimals.Theycancausecholicin
hoofedanimalsanddigestivedistressinallanimals.Theycanalsoirritatetheskin.
foxglove(2)
Thisplantcontainsdigitoxin,achemicalthatwillmakeyounauseated,thencauseseriousheartproblems.However,insmalldosesthischemicalisusedasaheartmedication.
larkspur(2)
Thetoxinsinthisplantcauseproblemstomusclesand
nerves,andcanbefatal.Thisplantcausesproblemsingraz-inganimals.Inlatesummer,theplantbecomeslesstoxic.
ferns(.5)
PeopleinAsiaeatfernfiddle-heads with no apparent ill ef-fects.However,allfernshavebeenshowntobecarcinogenicandtheyareprobablycontrib-utingtoJapan’shighratesof
digestivecancers.
ivy(1)
Ivyleavesandberriesaremild-lypoisonous,causingdigestivediscomfortandlaboredbreath-ing.Theirbittertastehelpstokeephumansfromeatingthem.
holly(1)
Hollylooksniceasaholidaydecoration,butdon’teatit.Itwillgiveyounausea,vomiting
and diarrhea.
cattails(0)
Allpartsofthecattailareed-ible.Somepeoplegrindtherootsintoaflour.Thestemsaretenderandtastelikecu-
cumber.Thebrownspikescanbeeatenlikecornonthecob.
whitesnakeroot(2)Allpartsofthisplantare
toxicduetoachemicalcalledtremetol,whichcausesseveretremblingandvomitingandcanbefatal.Thetoxincanpass
throughacow’sudderandintoitsmilkcausing“milksickness.”
jimsonweed(3)Likedeadlynightshade,jimsonweedcontainsachemical
calledatropine,whichinterfereswiththenormalfunctioningofthenervoussystem.Inverysmallamounts,thischemicalcanbeusedasamedicine.
ragwort(2)
Thisplantismostdangeroustograzinganimals.Itisbitterandthereforeunlikelytobecon-sumedbyhumans.Itcausesliverdamagebecauseofitsmanyalkaloidchemicals.
nettles(0)
Thoughtheyhaveareputa-tionforbeingnastystingers(becauseofthehairsontheirstems),cookingthemremovesthestingandmakesthemcom-
pletelyedible.
wildcarrots(1)Thecarrotswegrowinourgar-dens are far removed from their wildcousins.Itisadvisablenottoeatthingsyoufindinthewildthatlooklikecarrots.Theycan
bepoisonous.
dandelionleaves(0)Dandelionleavesareagreatsourceofvitamins,minerals,andfiber.Allpartsoftheplantareedible,eithercookedorraw.Manypeopleusetheleavesassaladgreens.
rhubarbleaves(1)Rhubarbleavescontainoxalicacid,whichcancausekidneydamage,convulsionsand
coma.However,you’dhavetoeatquiteafewofthemto
achievetheseextremeeffects.
tomatoleaves(1)Thesecontainsolanin,whichcancausestomachupset
and nervous system distress. Tomatoesareinthenightshadefamilyofplants,Solanaceae,alongwithAtropabelladonna,jimsonweed,andpotatoes.
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azalea(2)
Theazaleaisasmallrhododen-dron.Thenectaroftheazaleaflowersisalsotoxic,soifbeesmakehoneyfromazaleas,the
honeywillbetoxic.
hibiscus(0)
Hibiscusplantsarefamousfortheirhugeflowers.Sincetheflowersareedible,theycanbeusedasdisposableplates!
rhododendron(2)Rhododendronsarethelargergroupofplantstowhichazaleasbelong.Rhododendronsarelargebusheswithhugeball-
shapedflowers.Aslongasyoulookanddon’ttaste,you’reOK!
hydrangea(1.5)Hydrangeaaredistantlyrelatedtorhododendrons,butcontainthesametoxicchemicalsfoundin the Prunusfamily(fruitswithpits).Thesechemicalsmainlyaffectthedigestivesystem.
gooseberries(0)
Gooseberriesareoneofthefewsimple,roundberriesthatareedible.Theyarerelatedtocur-rants and are native to Europe andAfrica.Theyareusedinsalads,dessertsandjams.
asparagusberries(.5)
Asparagusberriesaresome-whatcontroversial,butthegen-eralconsensusistorefrainfromeatingthem,astheyhavebeenreportedtocausetoxiceffects.
pokeweedberries(1.5)
Thepokeweedplantisacom-monweed.Theripeberriesaredarkpurpleandcanbeusedasanaturaldye.Eatingmorethanafewberriescancausenausea
andheadache.
yewberries(2)Thesebrightredberriesare
foundonbushesthathavesoft,flatneedles,likeanevergreen.Eatingmorethanafewberriescancausevomiting,diarrheaanddizziness.Eatingalotof
themcanbefatal.
tulipbulbs(1)Mostofthetulipbulbismod-eratelytoxic.DuringWWII
peopleinHollandatetheouterpartsoftulipbulbswhenfacedwithstarvation.Theknewthecentralpartofthebulbwastoxic
and did not eat it.
orchidbulbs(0)
Orchidsarenotcloselyrelatedtotheseotherbulbs,sotheir
chemistryisdifferent.Allpartsoftheorchidplantareedibleandtheflowersareoftenusedin
salads and desserts.
daffodilbulbs(2)
Daffodilsarerelatedtotulipsbuttheirbulbsseemtobemoretoxicthantulipbulbs.Eatingdaffodilbulbscausesintense
vomitinganddiarrhea.
hyacinthbulbs(2)
Related to tulips and daffo-dils,hyacinthsarealsotobeavoided.Thealkaloidchemi-calscauseintensedigestive
misery,andcanalsoaffectothersystemsofthebody.
mapleleaves(2)Thesearemoreofadangertograzinganimalsthanpeople,ashorsesfindthemtastyandpeopledonot.Theleavesgetmoretoxicastheywiltandturncolors.Onlyafewpoundsof
them will poison a horse.
dogwoodleaves(0)
Theleavesandberriesofthedogwoodtreearenon-toxic.
cherryleaves(2)
Theleavesofthecherrytreecontainthesametoxicchemi-calsfoundintheseeds.Horseownersareverycarefultokeepcherrytreeleavesoutoftheir
animals’ pastures.
oakleaves(1)
Oakleavescontainhighlevelsoftannicacid,whichcausesdigestiveupsetandpossiblyothersymptomsathighdoses.Itcancausegrazinganimalstocholic.Pigsarenotaffected.
rawkidneybeans(2)Rawkidneybeanscontainasubstancecalledlectin,whichisbeneficialtotheplant,butnottoyou.Even4-6rawbeanscancausegreatdistresstoyour
digestivesystem.Boilingbeansfor10min.destroysthelectins.
rawlimabeans(1)
Rawlimabeanscontainasub-stancecalledlinamarin,whichisfairlytoxic.Whenboiledforjust10minutes,thischemicalisbrokendownandbecomes
harmless.
rawgreenbeans(.5)We’vealleatenafewrawgreenbeansonceinawhile.Don’tpanic!Afewwon’tharmyou.Justdon’teatabushelofrawbeansoryou’llgetsomedis-
tressingdigestivedisturbances.
rawMungbeans(0)Mungbeansbelongtothege-
nus VignaandcomefromIndia.TheotherbeansinthisrowaregenusPhaseolus and are native totheAmericas.Mungbeanscanbeeatenraworcooked.
cherrypits(1)AllmembersofthePrunus fam-ilyhavecyanogenicglycosidechemicalsthatattackthecellsinyourdigestivesystem.Alargedoesofthesechemicalscanaffectotherorgans,aswell.
grapeseeds(0)Grapeseedsarenotonlynon-toxicbuttheyarebeneficial.
Grapeseedextractisapowerfulanti-oxidant,protectingyour
cellsfromdangerousmoleculescalled“freeradicals.”
appleseeds(.5)
Appleseedscontainsmallamountsofatoxiccyanide
chemical,butyou’dhavetoeathundredsofseedstoproduceanynoticeablesymptoms.
pearseeds(.5)
Pear seeds have the same is-sueasappleseeds,sincetheyaresomewhatrelated.Again,eatinganoccasionalappleorpearseedisnotaproblem.
