The University of Southern Mississippi The Aquila Digital Community Faculty Publications 5-1991 Osmophores, Floral Features, and Systematics of Stanhopea (Orchidaceae) Kenneth J. Curry University of Southern Mississippi, [email protected] Lorraine M. McDowell University of Florida Walter S. Judd University of Florida, [email protected] William Louis Stern University of Florida Follow this and additional works at: https://aquila.usm.edu/fac_pubs Part of the Botany Commons Recommended Citation Curry, K. J., McDowell, L. M., Judd, W. S., Stern, W. L. (1991). Osmophores, Floral Features, and Systematics of Stanhopea (Orchidaceae). American Journal of Botany, 78(5), 610-623. Available at: https://aquila.usm.edu/fac_pubs/9 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Faculty Publications by an authorized administrator of The Aquila Digital Community. For more information, please contact [email protected]. Osmophores, Floral Features, and Systematics of Stanhopea (Orchidaceae) Author(s): Kenneth J. Curry, Lorraine M. McDowell, Walter S. Judd, William Louis Stern Reviewed work(s): Source: American Journal of Botany, Vol. 78, No. 5 (May, 1991), pp. 610-623 Published by: Botanical Society of America Stable URL: http://www.jstor.org/stable/2445082 . Accessed: 14/11/2011 09:49 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Botanical Society of America is collaborating with JSTOR to digitize, preserve and extend access to American Journal of Botany. http://www.jstor.org American Journalof Botany 78(5): 610-623. 1991. OSMOPHORES, FLORAL FEATURES, AND SYSTEMATICS OF STANHOPEA (ORCHIDACEAE)1 KENNETH J. CURRY,2 LORRAINE M. MCDOWELL,3 WALTER S. JUDD,3 AND WILLIAM Louis STERN3,4 2Departmentof Biological Sciences, University of Southern Mississippi, Hattiesburg,Mississippi 39406-5018; and 3Departmentof Botany, University of Florida, Gainesville, Florida 32611-2009 The floralfragrance glands (osmophores) of 18 speciesof Stanhopeaand Sievekingiawere examinedthrough a seriesof developmentalstudies at lightand electronmicroscope levels includinglate bud stagesthrough postanthesis. Various characters were identified to be of potentialsystematic value and were recorded for each species. These characters included: texture ofthe osmophore surface, number of distinct cell layerscomprising the osmophore, nature of lipidinclusions in osmophorecells, and presenceor absenceof plastoglobuliin osmophore amyloplasts.These characters were combined with traditional features of floral lip morphology forcladistic analysis. Sievekingia was thepostulated outgroup. Stanhopea ecornuta showed the largestnumber of plesiomorphic characters. Stanhopea pulla, S. annulata,and S. candidawere onlyslightly more derived. Stanhopea anfracta, S. gibbosa,S. martiana,S. oculata,S. radiosa, S. ruckeri,S. saccata,S. shuttleworthii,S. tigrina, S. vasquezii,and S. wardiiform a monophyletic groupthat can be recognized by a labellumwith an articulated epichile and a bicornuatemesochile (or hypochile).Stanhopea tricornis may be a hybridbetween a speciesof Sievekingiaand Stanhopea. StanhopeaFrost ex Hookeris thetype genus The genushas not been monographed,but of subtribeStanhopeinae which are all Neo- Dodson and Frymire(1961; hereinafterre- tropicalepiphytes pollinated exclusively by ferredto withoutyear) suggestedan evolu- male euglossinebees. Stanhopea,with about tionaryscheme (Fig. 1) thatincluded many of 50 species,is amongthe largest genera in the thespecies, and thegenus Sievekingia Reichb. subtribeand is characterizedby ribbedpseu- f. was suggestedas a possibleancestor from dobulbs,each bearing a single,plicate leaf. The whichStanhopea was derived.Dodson (1963, inflorescenceis directeddownward from the 1975a, b) has since publishedadditional in- base of the pseudobulb.There are two to 15 formationconcerning individual species of simultaneouslyopening flowers that last 1 or Stanhopea. Dressler(1981) reproducedthe 2 daysand are intenselyaromatic. The aroma originalevolutionary scheme (Dodson and is a combinationof terpenesand aromatics Frymire)with little basic change to incorporate (Williamsand Whitten,1983) produced by se- newdata on plant-pollinatorrelationships. In cretorytissue called the osmophore(Vogel, a recentpersonal communication, Dodson in- 1963). dicatedthe placementin his originalscheme Pollinationof plantsin thissubtribe is un- of some newlydescribed species. usual in thatthere is no foodreward for the Flowersof Sievekingiaare less specialized pollinator.Male euglossinebees are attracted thaneven the least specialized flower of Stan- to plantsby thefragrance produced in theos- hopea.A labellummay be distinguishedfrom mophore.Apparently, visual cues are second- the othertwo petalsby its morphologyand ary.Bees collectthe fragrance which they use thepresence of a callus,but it is notsufficiently presumablyas a precursorfor a sexpheromone differentiatedto definea hypochile,meso- (Dressler,1982). chile,or epichile,as is generallytrue in Stan- hopea.The proximalportion of thelabellum 1Received for publication 13 July1990; revisionac- behindthe callus forms a shallowpouch rem- cepted3 January1991. iniscentof the pouch in thehypochile of Stan- The authorsthank Henry C. Aldrichfor use ofthe Elec- hopea.The floorof this shallow pouch in the tronMicroscope Core Laboratory, University of Florida, labellumcontains the osmophoreof Sievek- andVicki A. Funk,Smithsonian Institution, for her review (Fig.-2). whichhelped us avoidcertain embarrassing discrepancies. ingia This studywas supportedin partby NSF grantsDEB 82- Classificationof Stanhopea is based almost 19120and BSR-8607212to WLS. exclusivelyon characteristicsof the labellum. 4Author forcorrespondence. In some speciesthe labellumhas become so 610 May 1991] CURRY ET AL. -OSMOPHORES AND SYSTEMATICS IN STANHOPEA 611 St. oculata St. tigrina St. martiana i St. bucephalus St. saccata St. wardii St insignis - - - - ~~~~~~St.grandiflora St. rodrigasiana St. connata / St. Iewisae ( - ~~St. reichenbachiana St. cirrhata St. tricornis / St. ecornuta \\ ~~I _ I - __-~- St. pulla Si. trollii Si. suavis Si. shepheardii Fig.1. RepresentationofDodson and Frymire's (1961) diagram of labella and columns of Stanhopea and Sievekingia suggestingrelationships among the species. specializedthat it may be divided forcon- withpollination. The labellumhas becomea venienceof reference and discussion into three centralfocus for Stanhopea taxonomy because parts:the proximalhypochile that includes itsvariability and structuralcomplexity allow theosmophore, the central mesochile (which theidentification of numerousfairly constant may be indistinguishablein some speciesof charactersthat may be used in speciesdelim- Stanhopea),and thedistal epichile. The more itation. specializedlabella have a mesochilebearing We considerthe evolutionary scheme (Fig. a pair of forward-projectinghorns. The epi- 1) proposedby Dodson and Frymire, including chileis articulatedto themesochile when that thepossible ancestral relationship with Sieve- structureis present.Petals of Stanhopea flow- kingia,to be a usefulworking hypothesis. Al- ers (excludingthe labellum)are stronglyre- thoughthey did not addressthe issue, their flexedin all butone species.The columnarch- evolutionaryscheme, if accepted,would lead es parallelalong the labellum, and its terminal to the considerationof Sievekingiaas likely antherlies in close proximityto theepichile. paraphyletic,with Stanhopea being the sister Dodson and Frymiresuggested that floral groupof a species(or clade) within Sievekingia. charactersintimately associated with pollina- The questionof themonophyly or paraphyly tionwould be understrong selective pressure, of Sievekingiais not addressedin our study, whereascharacters less importantto pollina- and wouldrequire the inclusion of additional tionwould be morevariable within a species. speciesof this genus, as wellas relatedgenera, Theycited high variability in coloras an ex- in the cladisticanalyses. We have examined, ampleof a characternot intimately associated throughdevelopmental studies, the osmo- 612 AMERICAN JOURNAL OF BOTANY [Vol. 78 I ~~~~~~~~~~~St.vasquezii St. oculata St. tigrina St. tricornis . \\ /t X St. saccata . e 5S I ' / pulla Si. suavis Si. marsupialis Fig. 2. Representativelabella in top and sagittalviews organized to depictour approximation of the evolutionary schemeproposed by Dodson and Frymire(1961). Sievekingia suavis is postulatedas closeto theancestor of Stanhopea. Stanhopeapulla typifiesprimitive members of thegenus. Stanhopea saccata and S. tigrinarepresent the "insignis" complex,and Stanhopeaoculata and S. vasqueziirepresent the "oculata" complex. Stanhopea tricornis is thoughtto be a hybridbetween Stanhopea and Sievekingia.Top and sagittalviews of labella for each speciesare drawnto scale; however,labella of the different species are notreproduced proportionately. Si = Sievekingia;St = Stanhopea. phoresof many species of Stanhopea and two MATERIALS AND METHODS species of Sievekingia.Herein we describe characteristicsof osmophoresof