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1、
atallnearthepithcavity.Thesetransversezonesvaryintheirwidthaccordingtospeciesandthicknessoftheculm,andtheinnerzonemayaltogetherbeabsentinsomespecies.Thevariationofvascularbundlesalongculmlength(height)ismoresignificantthantheradialone.
2、Theirform,sizeandpatterncanvarysodistinctlythataninternodefromtheculmbaseexhibitsacompletelydifferentstructurecomparedwithasamplefromthemiddlepartoftheculmwhich,inturn,maydifferconsiderablyfromonetakenatthetop(Fig.27).Thechangescoincidewiththegradualreductioni
3、nwallthickness.Forthecharacterizationofaspecies,itisnecessarytodescribethetissuepatternfromseveralinternodesatdifferentpositionsintheculm.Fromintensivestudiesofmorethan250culms,itcanbeconcludedthateveryfourthoreighthinternodeisadequate,dependingonthereductiono
4、fculmwallthickness.Thechangesfrominternodetointernodearemoreobviousinthelowerpartsthaninthemiddleandupperpartsoftheculm.However,unlikewoodanatomy,diagnosticdescriptioncanberestrictedtothecrosssection,sinceradialandtangentialsectionsofbambooculmsdonotexhibitany
5、distinguishingfeature.Inallbamboospeciesinvestigated,thesizeofvascularbundlesdecreasesfromthebasetothetopoftheculm.Astheirradialdiameterreducesmuchmorethanthetangentialdiameter,theshapeofvascularbundleschangesfromaradialelongatedformtoaroundishorovalformnearth
6、etop.Theextentofvariationintheformofvascularbundlesdiffersfromspeciestospecies.WhereasTypeIexistsexclusivelyinmonopodialgeneraandnevertogetherwithanyothertype,TypesII,IIIandIVoccurinsympodialgenera.TypeIIexistseitheralone,orcombinedwithTypeIIIinthelowerculmpar
7、ts.TypeIIIispresenteitheralone,orincombinationwithTypesIIorIV.ThebasicTypeIVismostlyrestrictedtothick-walledbasalinternodesoflarge-sizedbamboosandisalwaysfoundincombinationwithTypeIII(GrosserandLiese1971).Tocharacterizethetwo-dimensionalvariationofvascularbund
8、leswithinaculm,Grosser(1971)developedvascularbundlediagramsfor25speciesinwhichbundleshapeandfrequencyaregiveninhorizontalrowsforsuccessiveinternodes(seealsoGrosserand37%Fig.27:Cha
