The structure and function of orchid pollinaria

Abstract

Cohesive masses of pollen known as pollinia have evolved independently in two plant families — Orchidaceae and Asclepiadaceae. Yet, the bilateral symmetry of orchids has allowed a greater degree of specialization in pollination systems and a much greater diversity in the morphology of pollinaria — units comprising the pollinia(um) together with accessory structures for attachment to the pollinator. Pollinaria differ in the degree of cohesion of pollen in the pollinium, which may be soft, sectile (comprised of sub-units known as massulae) or hard. A single hard pollinium may contain more than a million pollen grains, yet pollen:ovule ratios in orchids are several orders of magnitude lower than in plants with powdery pollen due to the lack of wastage during transport to the stigma. Attachment of pollinia to the pollinator is usually achieved by means of a viscidium that adheres most effectively to smooth surfaces, such as the eyes and mouthparts of insects and beaks of birds. The stalk connecting a pollinium to the viscidium may be comprised of a caudicle (sporogenous in origin) and/or a stipe (derived from vegetative tissue), or be lacking altogether. Caudicles and stipes may undergo a gradual bending movement 20 s to several hours after withdrawal from the flower, the main function of which appears to be to reduce the possibility of geitonogamous pollination. Other mechanisms that promote outcrossing and pollen export in orchids include pollen carryover (achieved by sectile or soft pollinia), temporary retention of the anther cap, protandry and self-incompatibility (rare among orchids). Pollinaria ensure that large pollen loads are deposited on the stigma, thus enabling the fertilization of the large numbers of ovules in the flowers of Orchidaceae. Pollinaria also ensure efficient removal of pollen from the anther, minimal pollen wastage during transit, and a high probability of deposition on conspecific stigmas.

This is a preview of subscription content, log in to check access.

References

  1. Ackerman J. D. (1975) Reproductive biology ofGoodyera oblongifolia (Orchidaceae). Madrona 23: 191–198.

    Google Scholar 

  2. Ackerman J. D. (1995) An orchid flora of Puerto Rico and the Virgin Islands. Mem. N.Y. Bot. Gdn 73: 1–203.

    Google Scholar 

  3. Ackerman J. D., Mesler M. R. (1979) Pollination biology ofListera cordata (Orchidaceae). Amer. J. Bot. 6: 820–824.

    Google Scholar 

  4. Ackerman J. D., Williams N. H. (1980) Pollen morphology of the tribeNeottieae and its impact on the classification of the Orchidaceae. Grana 19: 7–18.

    Google Scholar 

  5. Ackerman J. D., Williams N. H. (1981) Pollen morphology of theChloraeinae (Orchidaceae: Diurideae) and related subtribes. Amer. J. Bot. 68: 1392–1402.

    Google Scholar 

  6. Ackerman J. D., Montalvo A. M. (1990) Shortand long-term limitations to fruit production in a tropical orchid. Ecology 71: 263–272.

    Google Scholar 

  7. Albert V. A. (1994) Cladistic relationships of the slipper orchids (Cypripedioideae: Orchidaceae) from congruent morphological and molecular data. Lindleyana 9: 115–132.

    Google Scholar 

  8. Alexandersson R. (1999) Reproductive biology of the deceptive orchidCalypso bulbosa. PhD thesis, University of Umea.

  9. Atwood J. T. (1986) The size of the Orchidaceae and the systematic distribution of epiphytic orchids. Selbyana 9: 171–186.

    Google Scholar 

  10. Bell G. (1985) On the function of flowers. Proc. Roy. Soc. Lond. B. 224: 233–265.

    Google Scholar 

  11. Bernhardt P. (1995) Observations on the floral biology ofPterostylis curta (Orchidaceae). Cunninghamia 5: 1–8.

    Google Scholar 

  12. Blackman S. J., Yeung E. C. (1983) Comparative anatomy of pollinia and caudicles of an orchid (Epidendrum). Bot. Gaz. 144: 331–337.

    Google Scholar 

  13. Borba E. L., Semir J. (1999) Temporal variation in pollinarium size after its removal in species ofBulbophyllum: a different mechanism preventing self-pollination in Orchidaceae. Plant Syst. Evol. 217: 197–204.

    Google Scholar 

  14. Burns-Balogh P. (1982) Generic redefinition in the subtribeSpiranthinae (Orchidaceae). Amer. J. Bot. 69: 1119–1132.

    Google Scholar 

  15. Burns-Balogh P. (1983) A theory on the Evolution of the exine in Orchidaceae. Amer. J. Bot. 69: 1119–1132.

    Google Scholar 

  16. Burns-Balogh P., Funk V. A. (1986) A phylogenetic analysis of the Orchidaceae. Smithsonian Contrib. Bot. 61: 1–79.

    Google Scholar 

  17. Burns-Balogh P., Bernhardt P. (1985) Evolutionary trends in the androecium of the Orchidaceae. Plant Syst. Evol. 149: 119–134.

    Google Scholar 

  18. Burns-Balogh P., Bernhardt P. (1988) Floral evolution and phylogeny in the tribe Thelymitreae (Orchidaceae: Neottioideae). Plant Syst. Evol. 159: 19–47.

    Google Scholar 

  19. Cameron K. M., Chase M. W., Whitten W. M., Kores P. J., Jarrell D. C., Albert V. A., Yukawa T., Hills G., Goldman D. H. (1999) A phylogenetic analysis of the Orchidaceae: evidence fromrbcL nucleotide sequences. Amer. J. Bot. 86: 208–224.

    Google Scholar 

  20. Catling P. M. (1983) Pollination of northeastern North AmericanSpiranthes (Orchidaceae). Can. J. Bot. 61: 1080–1093.

    Google Scholar 

  21. Catling P. M. (1990) Auto-pollination in the Orchidaceae. In: Arditti J. (ed.) Orchid biology, reviews and perspectives V. Timber Press, Portland, Oregon, pp. 121–158.

    Google Scholar 

  22. Catling P. M., Catling V. R. (1991) A synopsis of breeding systems and pollination in North American orchids. Lindleyana 6: 187–210.

    Google Scholar 

  23. Chase M. W. (1987) Systematic implications of pollinarium morphology inOncidium Sw.,Odontoglossum Kunth, and allied genera (Orchidaceae). Lindleyana 2: 8–28.

    Google Scholar 

  24. Chen S. C. (1982) The origin and early differentiation of the Orchidaceae. Acta Phytotaxon. Sin. 20: 1–22.

    Google Scholar 

  25. Chesselet P., Linder H. P. (1993) Pollen morphology of theDiseae (Orchidoideae: Orchidaceae). Grana 32: 101–110.

    Google Scholar 

  26. Cole F. R., Firmage D. H. (1984) The floral ecology ofPlatanthera blephariglottis. Am. J. Bot. 71: 700–710.

    Google Scholar 

  27. Cribb P. J. (1987) The GenusPaphiopedilum. Kew: Royal Botanic Gardens; Portland, U.K.

    Google Scholar 

  28. Cruden R. W. (1977) Pollen-ovule ratios: a conservative indicator of breeding systems in flowering plants. Evolution 31: 32–46.

    Google Scholar 

  29. Cruden R. W., Jensen K. G. (1979) Viscin threads, pollination efficiency and low pollen-ovule ratios. Amer. J. Bot. 66: 875–879.

    Google Scholar 

  30. Dafni A., Ivri Y. (1979) Pollination ecology of, and hybridization between,Orchis coriophora L. andO. collina Sol. ex. Russ. (Orchidaceae) in Israel. New Phytol. 83: 181–187.

    Google Scholar 

  31. Dafni A., Ivri Y. (1981) The flower biology ofCephalanthera longifolia (Orchidaceae) — pollen imitation and facultative floral mimicry. Plant Syst. Evol. 137: 229–240.

    Google Scholar 

  32. Dahlgren R. M. T., Clifford H. T., Yeo P. F. (1985) The families of the monocotyledons: structure, evolution, and taxonomy. Springer, Berlin.

    Google Scholar 

  33. Darwin C. (1877) The various contrivances by which orchids are fertlized by insects. 2nd edn. John Murray, London.

    Google Scholar 

  34. De Jong T. J., Klinkhamer P. G. L., Staalduinen M. J. (1992) The consequences of pollination biology for selection of mass or extended blooming. Funct. Ecol. 6: 606–615.

    Google Scholar 

  35. Dressler R. L. (1971) Dark pollinia in hummingbird-pollinated orchids, or do hummingirds suffer from strabismus? Am. Nat. 105: 80–83.

    Google Scholar 

  36. Dressler R. L. (1968) Pollination by euglossine bees. Evolution 22: 202–210.

    Google Scholar 

  37. Dressler R. L. (1981) The Orchids: Natural History and classification. Harvard University Press, Cambridge, Mass.

    Google Scholar 

  38. Dressler R. L. (1986) Features of pollinaria and orchid classification. Lindleyana 1: 125–130.

    Google Scholar 

  39. Dressler R. L. (1990) The Neottieae in orchid classification. Lindleyana 5: 2, 102–109.

    Google Scholar 

  40. Dressler R. L. (1993) Phylogeny and classification of the orchid family. Timber Press, Portland.

    Google Scholar 

  41. Ellstrand N. C. (1984) Multiple paternity within the fruits of the wild radish,Raphanus sativus. Evolution 123: 819–828.

    Google Scholar 

  42. Fitzgerald M. A., Calder D. M., Knox R. B. (1993) Secretory events in the freeze-substituted tapetum of the orchidPterostylis concinna FitzG. Plant Syst. Evol. [Suppl.] 7: 53–62.

    Google Scholar 

  43. Fitzgerald M. A., Barnes S. H., Blackmore S., Calder D. M., Knox R. B. (1994) Pollen development and cohesion in a mealy and a hard type of orchid pollinium. J. Plant Sci. 155: 481–491.

    Google Scholar 

  44. Freudenstein J. V. (1994) Gynostemium structure and relationhips of theCorallorhizinae (Orchidaceae: Epidendroideae). Plant Syst. Evol. 193: 1–19.

    Google Scholar 

  45. Freudenstein J. V. (1991) A systematic study of endothecial thickenings in the Orchidaceae. Amer. J. Bot. 78: 766–781.

    Google Scholar 

  46. Freudenstein J. V., Rasmussen F. N. (1996) Pollinium development and number in the Orchidaceae. Am. J. Bot. 83: 7, 813–824.

    Google Scholar 

  47. Freudenstein J. V., Rasmussen F. N. (1997) Sectile pollinia and relationships in the Orchidaceae. Plant Syst. Evol. 205: 125–146.

    Google Scholar 

  48. Freudenstein J. V., Rasmussen F. N. (1999) What does morphology tell us about orchid relationships? — A cladistic analysis. Amer. J. Bot. 86: 225–248.

    Google Scholar 

  49. Fritz A. L. (1990) Deceit pollination ofOrchis spitzelii (Orchidaceae) on the island of Gotland in the Baltic: a suboptimal system. Nord. J. Bot. 9: 577–587.

    Google Scholar 

  50. Gregg K. B. (1991) Defrauding the deceitful orchid: pollen collection by pollinators ofCleistes divaricata andC. bifaria. Lindleyana 6: 214–220.

    Google Scholar 

  51. Hagerup O. (1952) Bud autogamy in some southern orchids. Phytomorphology 2: 51–60.

    Google Scholar 

  52. Hapeman J. R., Inoue K. (1997) Plant-pollinator interactions and floral radiation inPlatanthera (Orchidaceae). In: Givnish T. J., Sytsma K. J. (eds.) Molecular evolution and adaptive radiation. Cambridge University Press, Cambridge, pp. 433–454.

    Google Scholar 

  53. Harder L. D., Wilson W. G. (1998) A clarification of pollen discounting and its joint effects with inbreeding depression on mating system evolution. Am. Nat. 152: 684–695.

    Google Scholar 

  54. Johansen B. (1990) Incompatibility inDendrobium (Orchidaceae). Bot. J. Linn. Soc. 103: 165–196.

    Google Scholar 

  55. Johnson S. D. (1994) Evidence for Batesian mimicry in a butterfly-pollinated orchid. Biol. J. Linn. Soc. 53: 91–104.

    Google Scholar 

  56. Johnson S. D. (1996) Bird pollination in South African species ofSatyrium (Orchidaceae). Plant Syst. Evol. 204: 91–98.

    Google Scholar 

  57. Johnson S. D. (1997) Insect pollination and floral mechanisms in South African species ofSatyrium (Orchidaceae). Plant Syst. Evol. 204: 195–206.

    Google Scholar 

  58. Johnson S. D., Bond W. J. (1994) Red flowers and butterfly pollination in the fynbos of South Africa. In: Arianoutsou M., Groves R. H. (eds.) Plant-animal interactions in Mediterranean-type ecosystems. Kluwer Academic Publishers, Dordrecht, pp. 137–148.

    Google Scholar 

  59. Johnson S. D., Bond W. J. (1997) Evidence for widespread pollen-limitation of fruiting success in Cape wildflowers. Oecologia 109: 530–534.

    Google Scholar 

  60. Johnson S. D., Liltved W. R. (1997) Hawkmoth pollination ofBonatea speciosa (Orchidaceae) in a South African coastal forest. Nord. J. Bot. 17: 5–10.

    Google Scholar 

  61. Johnson S. D., Nilsson L. A. (1999) Pollen carryover, geitonogamy and the evolution of deception in orchids. Ecology 80: 2607–2619.

    Google Scholar 

  62. Johnson S. D., Steiner K. E., Kurzweil H. (1994) Auto-pollination inDisa species (Orchidcaeae) of the Cape mountain cloud zone. Lindleyana 9: 3–6.

    Google Scholar 

  63. Johnson S. D., Linder H. P., Steiner K. E. (1998a) Phylogeny and radiation of pollination systems inDisa (Orchidaceae). Amer. J. Bot. 85: 402–411.

    Google Scholar 

  64. Johnson S. D., Steiner K. E., Whitehead V. B., Vogelpoel L. (1998b) Pollination ecology and maintenance of species integrity in co-occurringDisa racemosa L.f. andDisa venosa Sw. (Orchidaceae) in South Africa. Ann. Missouri Bot. Gard. 85: 231–241.

    Google Scholar 

  65. Judd W. S., Stern W. L., Cheadle V. I. (1993) Phylogenetic position ofApostasia andNeuwiedia (Orchidaceae). Bot. J. Linn. Soc. 113: 87–94.

    Google Scholar 

  66. Kores P. J., Cameron K. M., Molvray M., Chase M. (1997) The phylogenetic relationships of Orchidoideae and Spiranthoideae (Orchidaceae) as inferred fromrbcL plastid sequences. Lindleyana 12: 1–11.

    Google Scholar 

  67. Kress W. J. (1981) Sibling competition and evolution of pollen unit, ovule number, and pollen vector in angiosperms. Syst. Bot. 6: 101–112.

    Google Scholar 

  68. Kurzweil H., Johnson S. D. (1993) Auto-pollination ofMonadenia bracteata. S. Afr. Orchid. J. 24: 21–22.

    Google Scholar 

  69. Larson B. M. H., Barrett S. C. H. (1999) The ecology of pollen limitation in buzz-pollinatedRhexia virginica (Melastomataceae). J. Ecol. 87: 371–381.

    Google Scholar 

  70. Levin D. A. (1981) Dispersal versus gene flow in plants. Ann. Missouri Bot. Gard. 68: 233–253.

    Google Scholar 

  71. Levin D. A., Kerster H. W. (1974) Gene flow in seed plants. Evol. Biol. 7: 139–220.

    Google Scholar 

  72. Linder H. P., Kurzweil H. (1994) The phylogeny and classification of the Diseae (Orchidoideae: Orchidaceae). Ann. Missouri Bot. Gard. 81: 687–713.

    Google Scholar 

  73. Mehroff L. A. (1983) Pollination in the genusIsotria (Orchidaceae). Amer. J. Bot. 70: 1444–1453.

    Google Scholar 

  74. Morse D. H. (1981) Modification of bumblebee foraging: the effect of milkweed pollinia. Ecology 62: 89–97.

    Google Scholar 

  75. Nazarov V. V., Gerlach G. (1997) The potential seed productivity of orchid flowers and peculiarities of their pollination systems. Lindleyana 12: 188–204.

    Google Scholar 

  76. Neiland M. R. M., Wilcock C. C. (1995) Maximization of reproductive success by European Orchidaceae under conditions of infrequent pollination. Protoplasma 187: 39–48.

    Google Scholar 

  77. Newton G. D., Williams N. H. (1978) Pollen morphology of the Cypripedioideae and the Apostasioideae (Orchidaceae). Selbyana 2: 169–182.

    Google Scholar 

  78. Nierenberg L. (1972) The mechanism for the maintenance of species integrity in sympatrically occurring Oncidiums in the Caribbean. Amer. Orch. Soc. Bull. 41: 873–882.

    Google Scholar 

  79. Nilsson L. A. (1980) The pollination ecology ofDactylorhiza sambucina (Orchidaceae). Bot. Notiser 133: 367–385.

    Google Scholar 

  80. Nilsson L. A. (1983a) Anthecology ofOrchis mascula (Orchidaceae). Nord. J. Bot. 3: 157–179.

    Google Scholar 

  81. Nilsson L. A. (1983b) Processes of isolation and introgressive interplay betweenPlatanthera bifolia (L.) Rich. andP. chlorantha (Custer) Reichb. (Orchidaceae). Bot. J. Linn. Soc. 87: 325–350.

    Google Scholar 

  82. Nilsson L. A. (1992) Orchid pollination biology. Trends Ecol. Evol. 7: 255–259.

    Google Scholar 

  83. Nilsson L. A., Jonsson L., Rason L., Randrianjohany E. (1985) The pollination ofCymbidiella flabellata (Orchidaceae) in Madagascar: a system pollinated by sphecid wasps. Nord. J. Bot. 6: 411–422.

    Google Scholar 

  84. Nilsson L. A., Rabakonandrianina E., Razananaivo R., Randriamanindry J. (1992a) Long pollinia on eyes: hawk-moth pollination ofCynorkis uniflora Lindley (Orchidaceae) in Madagascar. Bot. J. Linn. Soc. 109: 145–160.

    Google Scholar 

  85. Nilsson L. A., Rabakonandrianina E., Pettersson B. (1992b) Exact tracking of pollen transfer and mating in plants. Nature 360: 666–667.

    Google Scholar 

  86. O'Connell L. M., Johnston M. O. (1998) Male and female pollination success in a deceptive orchid, a selection study. Ecology 79: 1246–1260.

    Google Scholar 

  87. Pacini E., Franchi G. G. (1996) Some cytological, ecological and evolutionary aspects of Pollination. Acta Societatis Botanicorum Poloniae 65: 11–16.

    Google Scholar 

  88. Pacini E., Franchi G. G. (1998) Pollen dispersal units, gynoecium and pollination. In: Owens S. J., Rudall P. J. (eds.) Reproductive biology. Royal Botanic Gardens, Kew, pp. 183–195.

    Google Scholar 

  89. Pandolfi T., Pacini E. (1995) The pollinium ofLoroglossum hircinum (Orchidaceae) between pollination and pollen tube emission. Plant Syst. Evol. 196: 141–151.

    Google Scholar 

  90. Peakall R. (1989a) A new technique for monitoring pollen flow in orchids. Oecologia 79: 361–365.

    Google Scholar 

  91. Peakall R. (1989b) The unique pollination ofLeporella fimbriata (Orchidaceae): pollination by pseudocopulating male ants (Myrmecia urens, Formicidae). Plant Syst. Evol. 167: 137–148.

    Google Scholar 

  92. Peakall R., Beattie A. J. (1991) The genetic consequences of worker ant pollination in a self-compatible, clonal orchid. Evolution 45: 1837–1848.

    Google Scholar 

  93. Peakall R., Beattie A. J. (1996) Ecological and genetic consequence of pollination by sexual deception in the orchidCaladenia tentactulata. Evolution 50: 2207–2220.

    Google Scholar 

  94. Proctor H. C. (1997) Effect of pollen age on fruit set, fruit weight, and seed set of three orchid species. Can. J. Bot. 76: 420–427.

    Google Scholar 

  95. Proctor H. C., Harder L. D. (1994) Pollen load, capsule weight, and seed production in three orchid species. Can. J. Bot. 72: 249–255.

    Google Scholar 

  96. Rademaker M. C. J., De Jong T. J., Klinkhamer P. G. L. (1997) Pollen dynamics of bumble-bee visitation onEchium vulgare. Funct. Ecol. 11: 554–563.

    Google Scholar 

  97. Rasmussen F. N. (1982a) The gynostemium of neottioid orchids. Opera Bot. 69: 1–96.

    Google Scholar 

  98. Rasmussen F. N. (1982b) The gynostemium ofBulbophyllum ecornutum. Bot. J. Linn. Soc. 91: 447–456.

    Google Scholar 

  99. Rasmussen F. N. (1986a) On the contrivances by which pollinia are attached to viscidia. Lindleyana 1: 21–32.

    Google Scholar 

  100. Rasmussen F. N. (1986b) Ontogeny and phylogeny in Orchidaceae. Lindleyana 1: 114–124.

    Google Scholar 

  101. Robertson A. W. (1992) The relationship between floral display size and geitonogamy inMysotis colensoi (Kirk) MacBride (Boraginaceae). Biol. J. Linn. Soc. 46: 333–349.

    Google Scholar 

  102. Romero G. A. (1990) Phylogenetic relationships in subtribe Catasetinae (Orchidaceae, Cymbidieae). Lindleyana 5: 160–181.

    Google Scholar 

  103. Romero G. A., Nelson C. E. (1986) Sexual dimorphism inCatasetum orchids: forcible pollen emplacement and male flower competition. Science 232: 1538–1540.

    Google Scholar 

  104. Roubik D. W. (2000) Deceptive orchids with Meliponini as pollinators. Plant Syst. Evol. 222: 271–279.

    Google Scholar 

  105. Salguero-Faría J., Ackerman J. D. (1999) A nectar reward: is more better. Biotropica 31: 303–311.

    Google Scholar 

  106. Sanford W. W. (1964) Sexual compatibility relationships inOncidium and related genera. Amer. Orchid Soc. Bull. 33: 1035–1048.

    Google Scholar 

  107. Schill R. (1978) Palynologische Untersuchungen zur systematischen Stellung der Apostasiaceae. Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 99: 353–362.

    Google Scholar 

  108. Schill R., Dannenbaum C., Neyer P. (1992) Quantitative Untersuchungen an Orchideen-pollinien. Bot. Jahrb. Syst. 114: 153–171.

    Google Scholar 

  109. Schill R., Pfeiffer W. (1977) Untersuchungen an Orchideenpollinien unter besonderen Beruecksichtigung ihrer Feinskulpturen. Pollen et Spores 19: 5–118.

    Google Scholar 

  110. Schill R., Wolter M. (1986) Ontogeny of elastoviscin in the Orchidaceae. Nord. J. Bot. 5: 575–580.

    Google Scholar 

  111. Scott J. (1865) On the individual sterility and crossimpregnation of certain species ofOncidium. Bot. J. Linn. Soc. 8: 162–167.

    Google Scholar 

  112. Steiner K. E. (1989) The pollination ofDisperis (Orchidaceae) by oil-collecting bees in southern Africa. Lindleyana 4: 164–183.

    Google Scholar 

  113. Thomson J. D., Thomson B. A. (1989) Dispersal ofErythronium grandiflorum pollen by bumblebees: implications for gene flow and reproductive success. Evolution 43: 657–661.

    Google Scholar 

  114. Tremblay R. L. (1991) Trends in the pollination ecology of the Orchidaceae: evolution and systematics. Can. J. Bot. 70: 642–650.

    Google Scholar 

  115. Tremblay R. L. (1994) Frequency and consequences of multi-parental pollinations in a population ofCypripedium calceolus var.pubescens (Orchidaceae). Lindleyana 9: 161–167.

    Google Scholar 

  116. Stern W. L., Cheadle V. I., Thorsch J. (1993) Apostasiads, systematic anatomy, and the origins of Orchidaceae. Bot. J. Linn. Soc. 111: 411–455.

    Google Scholar 

  117. Thomson J. D., McKenna M. A., Cruzn M. B. (1989) Temporal patterns of nectar and pollen production inAralia hispida: implications for reproductive success. Ecology 70: 1061–1068.

    Google Scholar 

  118. Van der Pijl L., Dodson C. H. (1966) Orchid flowers: their pollination and evolution. University of Miami Press.

  119. Warford N. (1992) Pollination biology: the reciprocal agreement betweenNotylia andEuglossa viridissima. Amer. Orchid. Soc. Bull. 61: 884–889.

    Google Scholar 

  120. Williams N. H. (1972) A reconsideration ofAda and the glumaceous brassias. Brittonia 24: 93–110.

    Google Scholar 

  121. Williams N. H., Broome C. R. (1976) Scanning electron microscope studies of orchid pollen. Amer. Orchid. Soc. Bull. 45: 699–707.

    Google Scholar 

  122. Williamson G. (1984) Observations of a mechanism by which self-pollination may occur inEulophia (Orchidaceae). J. S. Afr. Bot. 50: 417–423.

    Google Scholar 

  123. Zavada M. S. (1990) A contribution to the study of pollen wall ultrastructure of orchid pollinia. Ann. Missouri Bot. Gard. 77: 785–801.

    Google Scholar 

Download references

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Johnson, S.D., Edwards, T.J. The structure and function of orchid pollinaria. Pl Syst Evol 222, 243–269 (2000). https://doi.org/10.1007/BF00984105

Download citation

Key words

  • Orchidaceae
  • geitonogamy
  • gene flow
  • pollen
  • pollen discounting
  • pollen:ovule ratio
  • pollinaria
  • pollination
  • pollinium
  • seed size
  • self-incompatibility