Areolar structure in some Opuntioideae: occurrence of mucilage cells in the leaf-glochid transition forms in Opuntia microdasys (Lhem.) Pfeiff.

[摘要] OneofthemostremarkablefeaturesofCactaceaearetheareoles,axillaryoutgrowths,whichproducetrichomes,spinesandleaves.ThesubfamilyOpuntioideaeK.Schum.showsthewidestdiversityoftransitionformsbetweenleavesandspines,whichrepresentsanatomicalevidencethatspinesandglochidsaremodifiedleaves.ThepurposeofthispaperistoprovideananatomicaldescriptionoftheareolarstructureinfourspeciesofOpuntioideae,inorderthatnewanatomicalhomologybetweenspines/glochidsandleavesmaybeclarified.Differentpatternsofareolemorphologyareobserved:1)Austrocylindropuntiasubulata(Muehl.)Backeb.showingtereteandpersistentleaves;areoleswithpersistentspines,glochidsandtrichomes;2)Opuntiamonacantha(Willd.)Haw.withteretecaducousleavesandpersistentspines,glochidsandtrichomes;3)OpuntiarufidaEngelm.withteretedeciduousleavesandareoleswithglochidsandtrichomes;and4)Opuntiamicrodasys(Lhem.)Pfeiff.withearlycaducousleavesandareolesshowingtrichomesandleaf-spineandleaf-glochidtransitionforms.Thedevelopmentoftheareolarstructuresisverysimilarinallspecies,followingthedescriptionoftheliteratureforotherCactaceaeJuss.InO.microdasysisdescribedanewanatomicalcharacterinthefamily:mucilagecellsintheleaf-glochidtransitionforms,whichmayhavefunctionalimportanceforwaterstorageinspeciesdevoidofpersistentleaves.

[学科分类] 植物学

[关键词] Cactaceae;modified leaves;anatomical homology;Cactaceae;feuilles modifiées;homologie anatomique