Protoplasma

, Volume 187, Issue 1–4, pp 39–48 | Cite as

Maximisation of reproductive success by European orchidaceae under conditions of infrequent pollination

  • M. R. M. Neiland
  • C. C. Wilcock
Article
Received:
Accepted:

Summary

The pollination biology of a group of European orchids (Dactylorhiza, Ophrys, Orchis, Platanthera, Goodyera, andSerapias species) are investigated, and their anthecological characteristics considered in relation to natural levels of reproductive success. Pollen ∶ ovule (P ∶ O) ratios of the European orchids surveyed range from 10 ∶ 1 (Goodyera repens) to 24 ∶ 1 (Platanthera chlorantha). Average pollen-load ∶ ovule ratios are consistently lower than P ∶ O ratios. Naturally occurring pollen loads range from 1 massula to >1 pollinium. Even the smallest pollen load is sufficient to stimulate embryogenesis in experimentally pollinatedDactylorhiza purpurella flowers, although more seeds are set with larger loads. Pollen tubes grow rapidly through the stylar canal and into the top of the ovary within 2 or 3 days of pollination, and grow down either side of the 3 parietal ridges in the ovary. Fertilisation occurs throughout the length of the ovary but its distribution is non-random, especially when pollen loads are limiting, with more seeds being set at the stylar end. All species ofDactylorhiza, Ophrys, andOrchis studied are highly self-compatible. In the absence of pollination,Ophrys andOrchis flowers remain open and fertile for at least 3 weeks. Pollinated flowers remain receptive to further pollinations for at least 8 days. Some fruits can even be obtained on selfing 20-day-old unpollinatedOrchis morio flowers. Excised pollinia retain germinability for a long time, up to 51 days inDactylorhiza purpurella. The arrival of pollen on the stigma hastens floral senescence, but post-pollination changes are relatively slow when compared with those reported for tropical orchid species. It is concluded that characteristics of the pollination biology of European orchids act to maximise reproductive success by (1) prolonging the opportunity for effective pollen deposition both pre- and post-pollination, (2) increasing the likelihood of widespread dispersal, (3) reducing pollen wastage, and (4) increasing seed quality by promoting some pollen competition. As most European orchids are xenogamous and require pollen to arrive on the stigma before seed can be set, reproductive maximisation is of particular adaptive advantage because many of them are infrequently visited by insects so that the probability of successful pollination can be very low.

Keywords

Orchid pollinia Pollination limitation Reproductive maximisation Post-pollination events Pollen longevity Pollen loads 

Abbreviations

P ∶ O

pollen ∶ ovule ratio

PL ∶ O

pollen-load ∶ ovule ratio

FCR

fluorochromatic reaction test

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

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Afzelius K (1928) Die Embryobildung beiNigritella nigra. Sv Bot Tidskr 22: 82–91Google Scholar
  2. Ackerman JD, Montalvo AM (1990) Short- and long-term limitations to fruit production in a tropical orchid. Ecology 71: 263–272Google Scholar
  3. —, Montero Oliver JC (1985) Reproductive biology ofOncidium variegatum: moon phases, pollination and fruit set. Am Orchid Soc Bull 54: 326–329Google Scholar
  4. Arditti J (1976) Post-pollination phenomenon in orchid flowers. Orchid Rev 84: 261–268Google Scholar
  5. — (1979) Aspects of the physiology of orchids. Adv Bot Res 7: 421–697Google Scholar
  6. — (1992) Fundamentals of orchid biology. Wiley, New YorkGoogle Scholar
  7. Bierzychudek P (1981) Pollinator limitation of plant reproductive effort. Am Nat 117: 838–840Google Scholar
  8. Brewbaker JL, Majamder SK (1961) Cultural studies of the pollen population effect and the self-incompatibility inhibition. Amer J Bot 48: 457–464Google Scholar
  9. Catling PM, Catling VR (1991) A synopsis of breeding systems and pollination in North American orchids. Lindleyana 6: 187–210Google Scholar
  10. Cocucci A, Jensen WA (1969) Orchid embryology: megagametophyte ofEpidendrum scutella following fertilization. Amer J Bot 56: 629–640Google Scholar
  11. Cruden RW (1976) Pollen-ovule ratios: a conservative indicator of breeding systems in flowering plants. Evolution 31: 32–46Google Scholar
  12. —, Jensen KG (1979) Viscin threads, pollination efficiency and low pollen-ovule ratios. Amer J Bot 66: 875–879Google Scholar
  13. Curtis JT, Duncan RE (1947) Studies on the germination of orchid pollen. Am Orchid Soc Bull 16: 594–597, 616–619Google Scholar
  14. Dafni A, Calder DM (1987) Pollination by deceit and floral mimicry inThelymitra antennifera. Plant Syst Evol 158: 11–22Google Scholar
  15. Darwin C (1888) The various contrivances by which orchids are fertilised by insects, 2nd edn. J Murray, LondonGoogle Scholar
  16. Davis RW (1986) The pollination biology ofCypripedium acaule (Orchidaceae). Rhodora 88: 445–450Google Scholar
  17. Dressler RL (1990) The orchids. Natural history and classification, 2nd edn. Harvard University Press, CambridgeGoogle Scholar
  18. Fredrikson M, Carlsson K, Franksson O (1988) Confocal scanning laser microscopy, a new technique used in an embryological study ofDactylorhiza maculata (Orchidaceae). Nord J Bot 8: 369–374Google Scholar
  19. Gori DF (1983) Post-pollination phenomena and adaptive floral changes. In: Jones CE, Little RJ (eds) Handbook of experimental pollination biology. Van Nostrand Reinhold, New York, pp 31–49Google Scholar
  20. Gregg KB (1991) Reproductive strategy ofCleistes divaricata (Orchidaceae). Amer J Bot 78: 350–360Google Scholar
  21. Hagerup O (1947) The spontaneous formation of haploid, polyploid and aneuploid embryos in some orchids. Det Kgl Danske Videnske Selsk Biol Medd 20: 1–22Google Scholar
  22. Heslop-Harrison J, Heslop-Harrison Y, Shivanna KR (1983) The evaluation of pollen quality, and a further appraisal of the fluorochromatic (FCR) procedure. Theor Appl Genet 67: 367–375Google Scholar
  23. Hill JP, Lord EM (1986) Dynamics of pollen tube growth in the wild radish,Raphanus raphanistrum (Brassicaeae) I. Order of fertilization. Evolution 40: 1328–1333Google Scholar
  24. Johansen B (1990) Incompatibility inDendrobium (Orchidaceae). Bot J Linn Soc 103: 165–196Google Scholar
  25. Kevan PG, Eisikovitch D, Rathwell B (1989) The role of nectar in the germination of pollen inAsclepias syriaca L. Bot Gaz 150: 266–270Google Scholar
  26. Mehrhoff LA (1983) Pollination in the genuslsotria (Orchidaceae). Amer J Bot 70: 1444–1453Google Scholar
  27. Mulcahy DL, Curtis PS, Snow AA (1983) Pollen competition in a natural population. In: Jones CE, Little RJ (eds) Handbook of experimental pollination biology. Van Nostrand Reinhold, New York, pp 303–337Google Scholar
  28. —, Mulcahy GB (1987) The effects of pollen competition. Am Sci 75: 44–50Google Scholar
  29. Neiland MRM (1994) Reproductive ecology of British and Mediterranean orchids. PhD thesis, University of Aberdeen, Aberdeen, ScotlandGoogle Scholar
  30. - Wilcock CC (1993) The reproductive ecologyof Dactylorhiza lapponica in Scotland. Scottish Natural Heritage Report, EdinburghGoogle Scholar
  31. — — (1994) Reproductive ecology of European orchids. In: Pridgeon A (ed) Proceedings of the 14th World Orchid Conference. HMSO, London, pp 138–147Google Scholar
  32. Nilsson LA (1979) Anthecological studies on the Lady's Slipper,Cypripedium calceolus (Orchidaceae). Bot Notiser 132: 329–347Google Scholar
  33. Ottaviano E, Sari-Gorla M, Mulcahy DL (1980) Pollen tube growth rates inZea mays: implications for genetic improvement of crops. Science 210: 437–438Google Scholar
  34. Pais MSS (1969) Morphologie, structure et cytochemie de la surface stigmatique d'Ophrys lutea L. (Orchidee). Port Acta Biol Ser A 22: 339–346Google Scholar
  35. Peakall R (1989) A new technique for monitoring pollen flow in orchids. Oecologia 79: 361–365Google Scholar
  36. Primack RB (1985) Longevity of individual flowers. Annu Rev Eco Syst 16: 15–37Google Scholar
  37. Pritchard HW, Prendergast FG (1989) Factors influencing the germination and storage characteristics of orchid pollen. In: Pritchard HW (ed) Modern methods in orchid conservation. The role of physiology, ecology and management. Cambridge University Press, Cambridge, pp 1–16Google Scholar
  38. Rahman MA, Wilcock CC (1992) A new species ofPeriploca (Periplocaceae) from Bangladesh. Bot J Linn Soc 110: 373–377Google Scholar
  39. Rao AN, Chin LW (1972) Experimental studies in the germination of orchid pollen. Cellule 69: 291–308Google Scholar
  40. Snow AA (1986) Pollination dynamics inEpilobium canum (Onagraceae): consequences for gametophytic selection. Amer J Bot 73: 139–151Google Scholar
  41. —, Spira TP (1991) Pollen vigour and the potential for sexual selection in plants. Nature 352: 796–797Google Scholar
  42. Swamy BGL (1948) Agamospermy inSpiranthes cernua. Lloydia 2: 149–162Google Scholar
  43. — (1949) Embryological studies of the Orchidaceae II. Embryology. Am Mid Nat 41: 202–232Google Scholar
  44. Veyret Y (1974) Development of the embryo and the young seedling stages of orchids. In: Withner CL (ed) The orchids: scientific studies. Wiley, New York, pp 223–265Google Scholar
  45. Wirth MW, Withner CL (1959) Embryology and development in the Orchidaceae. In: Withner CL (ed) The orchids: a scientific surgery. Ronald Press, New York, pp 155–188Google Scholar
  46. Zhang XS, O'Neill SD (1993) Ovary and gametophyte development are coordinately regulated by auxin and ethylene following pollination. Plant Cell 5: 403–418Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • M. R. M. Neiland
    • 1
  • C. C. Wilcock
    • 1
  1. 1.Department of Plant and Soil ScienceUniversity of AberdeenAberdeenUK

Personalised recommendations