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MusingsonTheCooktownOrchid,DendrobiumbigibbumByJeffGlover TheCooktownOrchidissosynonymouswithQueenslandasthestate’sfloralemblemitisevenan‘anti-fatiguetrivia’questionatvarioussitesontheBruceHighwaythatrunsalongthecoastfromBrisbanetoCairns.ItiswidelyregardedasAustralia’smostattractiveendemicorchid.Formanypeopletheveryname‘CooktownOrchid’invokesimagesoftropicalrainforestsrunningdowntoseasfilledwithcoral,andbeacheswithwavingpalmtrees.However,thisisnotso,itisinsteadmostlyfoundintheverydifferentbiographicalzoneoftheopenforestsofCapeYorkPeninsular,ratherthangrowingintherenownedWetTropicstothesouthofCooktownasiswidelybelieved.(LavarackandGray,1992).

Asaresult,growingonthetipandthewesterndrysideofthepeninsularitshostsarethetreesoftheremnantpatchesofscrubsandmonsoonforests,nottropicalpalmsandotherrainforesttreesassomeexpect.Italsooccasionallycanbefoundgrowingonrockfacesthatareshadedfromtheextremesoftheafternoonsun.Thedistincteither,dryandhot,thenwetandhot,seasonsforthisregionhasramificationsforcollectorcultivation;particularlyforthosewishingtogrowitinthecooler,wetterinWintersouthernstates.Itmusthaveadryrestperiodtobesuccessfullygrownincoolwetclimates.WhenconsideringthisclimaticgrowthpatternanunderstandingcanalsobeformedastowhyitanditshugenumberofprogenyflowerinAutumnratherthaninSpringasdothemajorityofotherfloweringorchids.

TriviasignontheBruceHighwayThisisdirectlyaresultoftheseclimaticconditions.HavingreceivedabundantwaterfromthemonsooninSummer;onceinflower,andthenhopefullypollinated,itsseedsarelaterdispersedinthefavourablewetandhotseasonandsothecyclecontinuesagainnextSummer.AcheckonOrchidwizversion3Xshowsithas279primaryhybridsand3884progenies.Asaresult,itgoeswithoutsayingthatonewouldbehardpressedtofindaphalaenanthedendrobiumthatwouldnothaveDendrobiumbigibbuminitsfamilytree.Interestingly,intheGeographicalDistributionnoteonthisUSAderiveddatabase,HawaiiisalsolistedalongwithAustralia(Queensland)andNewGuineaasendemicregions.ThisremindsmeofthespielofatourguidewhenIwasoncevisitingHawaiipontificatingabouttheHawaiianMacadamiaNut(QueenslandNut)whichaccordingtohim,wasalsoapparentlyendemictoHawaii.

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Thisorchidishighlyvariableinvarietyandform,therearealsorecognizedsub-veritiesandsub-species(ssp.)andhistoricalsynonymsstillinuse;averitabletaxonomistsnightmare.Withoutdelvingtoofarintothisbotanist’sminefield,itissafealsotosaythatalbaformsarefarfromuncommonandthevery‘lightblue’form‘coerulea’isalsooftenseenincultivationinQueensland.Inaddition,thereisthequestionofDendrobiumphalaenopsiswhichwasonceregardedasasynonymforbiggibum;nomenclaturethatcanstillbefoundinuse.However,itisnowDen.bigibbumfma.alba(ownerTDean)formallyregardedasaseparatespecies.Aswell,byhumaninterventionthroughlinebreeding,manyplantshavebeenderivedinthismannerandtheresultantflowerslookinmyopinionliketheequivalentofsomeoutcomesofhumancosmeticsurgery.Justliketheoriginalsurgerypatient,‘LineBred’formsarealteredsomuchinshapethattheylooknothingliketheoriginalspeciesandaremoreakintomulti-levelhybrids.Similarly,bicolour,stripedandflaredsupposed‘CooktownOrchids’arenowexhibitedatshows,andinmyexperienceareonesurewaytogetintoa‘robustdiscussion’ifdoubtiscastupontheirauthenticity.Iheardonewagsaythatthe‘flared’versionwasendemictoPhuketandfoundgrowingwildinThairestaurants!Lamentably,suchisthepopularityofthislittle‘AussieGem’,everyorchidbreederworld-wideoverthepast5decadeshaswantedapieceoftheactionleadingtomuchconfusionastojustwhatnowistherealMcCoy.

Itisgenerallyacceptedthattherearethreedistinctvarietiesthatvaryenoughinstructuralformthatwarrantthisdistinction.Dendrobiumbigibbumvar.superbumisthemoreabundantandwiththelargestflowersandlongestcanes.WhilethenorthernformDendrobiumbigibbumvar.bigibbumhassmallerflowersandoftendisplaysawhitespotonthelabellum(LavarackandGray,1992).ThethirdrecognizedvarietyDendrobiumbigibbumvar.compactum,orbetterknownbythecolloquialsobriquetof‘DwarfCooktownOrchid’,isfoundgrowinginthecoastalrangessouthofMossman,FarNthQld.Inthepastthiswasthemostcontestedastowhetheritwasadistinctvariety,orjusttheresultofdifferentgrowingconditionsandotherenvironmentalfactors.However,overtheyearsitwasfoundthatitstillmaintainsitsdwarfhabitincultivationwhileothersfoundfurthernorthand

Dendrobiumbigibbumvarbigibbumdisplayingawhitetip.(Lavarack&Gray,1992

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inthewesternrangesoftheCapeYorkPeninsulardonot.Therefore,thisculturalexhibitionstronglylendstotheargumentthatitisindeedstructurallydifferentandislikewise,geneticallydistincttotheextenttowarrantthisclassification.(LavarackandGray,1992).Inaddition,to‘muddythewatersfurther’,aspreviouslynoted,albaformsoccurinallvarieties,soitisentirelyfeasibleandproventohaveaplantwiththenomenclatureofDendrobiumbigibbumvar.compactumfma.alba,inotherwordsawhiteDwarfCooktownOrchid.Yetanotherfeatureofthisendearing‘AussieWonder’isitspropensityfornotonlybreedinginartificialconditions,butitsnaturalpartnershipwithwhatcouldberegardedasthe‘AussieBattler’oforchids’,Dendrobiumdiscolor,alsoknownasthe‘GoldenOrchid’.Thisspeciesisfoundgrowinginmanydiverselocationssuchas,frommangroveswampstoopenforests,rangingtothetipofCapeYorktoCentralQueensland.Itisveryhardy,haslonglastingflowersandproducesmanyroot–ladenplantletsfromitsrobustcanesandcanformhugeclumpsontreesandrockfaceswhentheseadheretothehosts’surface.WhenfoundgrowingtogethertheygiveusthebeautifulbotanicalgiftofthenaturalhybridDendrobiumXsuperbiens,knowncolloquiallyas‘CurleyPink’.InitsnaturalsituationItis

AmodernphalaenantheDen.hybridderivedfromtheCooktownOrchidproducedfrominsectcrosspollinationandwindborneseeddispersal.Likemosthybridsitgainsthebestfrombothparents,inthiscase,thecolourfromDendrobiumbigibbumandtherobustness,flowerlongevity,and‘twisted’flowerstructurefromDendrobiumdiscolour.OnceestablishedItcanbequiteprolificthankstoitsplantletproducingpropensityalsoinheritedfromdiscolourandisfoundgrowinginmanygardensthroughoutQueenslandonhosttreessuchasPalmsandFrangipani.ThelatterareperfecthostastheytendtodefoliatetosomeextentinWinterincentralandsouthernQueenslandlocations,andthenprovideafullcanopyinSummerthatgivesprotectionfrom

Den.CurlyPinkintheauthor’sgardenshowingaseedpodandplantlet(kiekie),farright.

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theharshsunandheat.Manyoftheplantletsaregivenaway,andonreflectionthisprobablywasmyfirstknowledgeoforchidsasachild.Wehadahugefrangipanitreeinourbackyardwhichalwaysseemedtohavethepinkflowersoftheorchidsmingledwiththewhiteandyellowofthefrangipani.Lookingback,ittrulywasabeautifultropicalimagethatlingersinmymemory;onewhichwasreplicatedforothersmanytimesbythegiftofplantletstoneighboursandfriendsbymymother;wholatertoldmeourcropofCurleyPinkwasstartedfrommyNanna,whonotsurprisinglyalsohadaFrangipaniinheryardcoveredinCurleyPink.Naturally,Ihaveitinmygarden,andyes,onFrangipaniandPalmstrees.Ittrulyistheorchid-giftthatkeepsongiving.AsAustraliansandQueenslanderswecertainlycanbeproudofourCooktownOrchid’scontributiontotheOrchidWorld.It’sbeautifulcolours,varietalrange,shape,hardinessandfertilityareasourceofadmirationworld-wide.Especially,whencomingfromacontinentnotthoughtofasbeingahometobeautifulexoticendemicorchids.WemaynothavetheabundantgeneraandspeciesofAsiaandtheAmericas,butinDendrobiumbiggibumwedohaveoneofthebest.TherewouldbemanyanoverseasflowerindustrythatwouldnotbeinexistenceifitwasnotforthepresenceofthislittleAussieBreeder.IfyouwouldliketoseemoreofwhatQueenslandhastoofferincoloursotherthantheMaroonoffootballfame,keepaplaceonyourcalendarforSeptember14-15,2019astheRockhamptonOrchidSocietywillbehostingthe10th.Sub-TropicalOrchidCouncilConferenceandShow,inRockhampton,Australia’sfirsttropicalCityandTheBeefandBarraCapitalsituatedontheTropicofCapricornbythemightyFitzroyRiver.DetailsandupdateswillbeappearinginOrchidAustraliafromnowonandalsoontheRockhamptonOrchidSocietyInc.websitewww.rockhamptonorchidsociety.com.auWehopeyoucanjoinus;youmaynotbeabletoseeaCooktownorchidinthewild;butIknowtherearemanygardenswereaCurleyPinkmaybeonoffer.Thetriviaanswersign.SourcesCited:AustralianTropicalOrchids.BillLavarack&BruceGray.1992,Firth&FirthBooks.,Malanda,Qld.Australia.SourcesConsulted:GrowingAustralianOrchids.A.M.Brombery&B.Maloney.1998,KangarooPressPty.Ltd,EastRoseville,Australia.